As filed with the Securities
                                                      and Exchange Commission on
                                                      July 1, 2002 Registration
                                                      No: 333-85864

--------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                ------------------------------------------------

                                  PRE-EFFECTIVE
                                 AMENDMENT NO. 1
                                       To
                                    FORM S-3
                             REGISTRATION STATEMENT
                                      Under
                           THE SECURITIES ACT OF 1933

               --------------------------------------------------

                               UNOCAL CORPORATION
               (Exact name of registrant specified in its charter)

          Delaware                                    95-3825062
(State or other jurisdiction of           (I.R.S. Employer Identification No.)
 incorporation or organization)

                        2141 Rosecrans Avenue, Suite 4000
                          El Segundo, California 90245
                                 (310) 726-7600
               (Address, including zip code, and telephone number,
              including area code, of principal executive offices)

                             DENNIS P.R. CODON, ESQ.
         Senior Vice President, Chief Legal Officer and General Counsel
                        2141 Rosecrans Avenue, Suite 4000
                          El Segundo, California 90245
                                 (310) 726-7600
            (Name, address, including zip code, and telephone number,
                   including area code, of agent for service)

        Approximate date of commencement of proposed sale to the public: From
   time to time after the effective date of this Registration Statement.

If the only securities being registered on this form are being offered pursuant
to dividend or interest reinvestment plans, please check the following box. []




If any of the  securities  being  registered on this form are to be offered on a
delayed or continuous  basis  pursuant to Rule 415  under the  Securities Act of
1933, other than securities offered only in connection with dividend or interest
reinvestment plans, check the following box. [X]

If this form is filed to register additional securities for an offering pursuant
to Rule 462(b) under the Securities Act, check the following box and list the
Securities Act registration statement number of the earlier effective
registration statement for the same offering. []

If this form is a post-effective amendment filed pursuant to Rule 462(c) under
the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. []

If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. []





-----------------------------------------------------------------------------------------------------------------------------------
                         CALCULATION OF REGISTRATION FEE

                                                                                         

-------------------------------- ---------------------- ------------------- ------------------------ -----------------
-------------------------------                          Proposed maximum      Proposed maximum         Amount of
    Title of each class of           Amount to be         offering price      aggregate offering       registration
  securities to be registered         registered           per unit(1)             price(1)               fee(2)
-------------------------------- ---------------------- ------------------- ------------------------ -----------------
-------------------------------- ---------------------- ------------------- ------------------------ -----------------
Common Stock, $1.00 par value       972,242 shares            $38.24              $37,178,534              $3,421
per share (including Preferred
Stock Purchase Rights)
-------------------------------- ---------------------- ------------------- ------------------------ -----------------


(1) Solely for the purpose of calculating the registration fee in accordance
with Rule 457(c), based upon the average of the high and low prices reported in
the consolidated reporting system for April 4, 2002.
(2) Fee of $4,047 paid on April 8, 2002 with original filing.



THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR DATES
AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT SHALL FILE
A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION STATEMENT
SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF THE
SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(A),
MAY DETERMINE.



                              Subject to Completion
                    Preliminary Prospectus Dated July 1, 2002


                             PRELIMINARY PROSPECTUS

THE INFORMATION IN THIS PRELIMINARY PROSPECTUS IS NOT COMPLETE AND MAY BE
CHANGED. THE SELLING STOCKHOLDERS MAY NOT SELL MAY NOT SELL THESE SECURITIES
UNTIL THE REGISTRATION STATEMENT FILED WITH THE SECURITIES AND EXCHANGE
COMMISSION IS EFFECTIVE. THIS PRELIMINARY PROSPECTUS IS NOT AN OFFER TO SELL
THESE SECURITIES AND IT IS NOT SOLICITING AN OFFER TO BUY THESE SECURITIES IN
ANY STATE WHERE THE OFFER OR SALE IS NOT PERMITTED.

                               UNOCAL CORPORATION
                         972,242 SHARES OF COMMON STOCK

This Prospectus relates to 972,242 shares of common stock of Unocal Corporation,
a Delaware corporation, which may be offered and resold from time to time by the
selling stockholders listed below (the "Selling Stockholders"). They obtained
the shares through the Unocal Executive Stock Purchase Plan which was approved
by stockholders in 2000.

We anticipate that the Selling Stockholders will offer shares for sale at prices
prevailing on the New York Stock Exchange on the date of sale. We will not
receive any of the proceeds from the sale of the securities covered by this
Prospectus. The Selling Stockholders will pay all selling and other expenses, if
any, associated with any sale of the shares. We will pay all of the expenses of
registration incurred in connection with this offering.

Each Selling Stockholder and any broker executing selling orders on behalf of
them may be deemed an "underwriter" within the meaning of the Securities Act of
1933, as amended, in which event commissions received by such broker may be
deemed to be underwriting commissions under the Securities Act.

Our common stock is traded on the New York Stock Exchange under the symbol
"UCL." On June 28, 2002, the last reported sale price of our common shares on
the NYSE was $36.94 per share.

See "Risk Factors" beginning on page 1 to read about some of the factors you
should consider before buying shares of Unocal common stock.

Our principal executive offices are located at 2141 Rosecrans Avenue, Suite
4000, El Segundo, California 90245 and our telephone number is (310) 726-7600.

NEITHER THE SECURITIES AND EXCHANGE COMMISSION NOR ANY STATE SECURITIES
COMMISSION HAS APPROVED OR DISAPPROVED OF THESE SECURITIES OR PASSED UPON THE
ADEQUACY OR ACCURACY OF THIS PROSPECTUS. ANY REPRESENTATION TO THE CONTRARY IS A
CRIMINAL OFFENSE.


You should rely only on the information contained or incorporated by reference
in this Prospectus. We have not authorized anyone else to provide you with
different information. If anyone provides you with different information, you
should not rely on it. The Selling Stockholders are not making an offer to sell
these securities in any jurisdiction where the offer or sale is not permitted.
You should assume that the information appearing in this prospectus or any
documents incorporated by reference is accurate only as of the date on the front
cover of the applicable document or as specifically indicated in the document.
Our business, financial condition, results of operations and business prospects
may have changed since that date.

                  The date of this Prospectus is ______, 2002.











                                TABLE OF CONTENTS


SPECIAL NOTE ON FORWARD-LOOKING STATEMENTS..............................       1

UNOCAL..................................................................       1

RISK FACTORS............................................................       1

USE OF PROCEEDS.........................................................      10

SELLING STOCKHOLDERS....................................................      10

PLAN OF DISTRIBUTION....................................................      12

LEGAL MATTERS...........................................................      12

EXPERTS.................................................................      13

WHERE YOU CAN FIND MORE INFORMATION.....................................      13

SIGNATURES..............................................................      17


                                       (i)


                   SPECIAL NOTE ON FORWARD-LOOKING STATEMENTS

Some of the statements contained in or incorporated by reference in this
prospectus discuss our plans and strategies for our business or state other
forward-looking statements, as this term is defined in the Private Securities
Litigation Reform Act of 1995. All statements, other than statements of
historical facts, that address activities, events or developments that we
intend, expect, project, believe or anticipate will or may occur in the future
are forward-looking statements. The words "believes," "anticipates," "believes,"
"estimates," "expects," "plans," "intends" and similar expressions are intended
to identify these forward-looking statements, but are not the exclusive means of
identifying them. These statements are based on assumptions and assessments made
by our management in light of its experience and its perception of historical
trends, current conditions, expected future developments and other factors our
management believes to be appropriate. These forward-looking statements are
subject to a number of risks and uncertainties, some of which our management has
not yet identified. Any such forward-looking statements are not guarantees of
future performances and actual results, developments and business decisions may
differ from those envisaged by such forward-looking statements as the result of
various important factors, certain of which but not all of which are discussed
at pages 51-53 of our 2001 Annual Report on Form 10-K and in other documents
incorporated by reference in this Prospectus.

                                     UNOCAL

We were incorporated in Delaware in 1983 to operate as the parent company of
Union Oil Company of California ("Union Oil"), which was incorporated in
California in 1890. We conduct substantially all of our operations through Union
Oil and its subsidiaries.

We are one of the  world's  largest  independent  oil and  gas  exploration  and
production  companies,  with principal operations in North America and Asisa. We
are also a leading  producer of  geothermal  energy and a provider of electrical
power in Asia.  Other  activities  include  ownership in proprietary  and common
carrier pipelines,  natural gas storage facilities and the marketing and trading
of hydrocarbon commodities.

Our principal executive offices are located at 2141 Rosecrans Avenue, Suite
4000, El Segundo, California 90245, and the telephone number at that address is
(310) 726-7600.

                                  RISK FACTORS

If you purchase our common stock, you will incur financial risk. Before buying
our stock in this offering, you should carefully consider the risks described
below, as well as other information contained in this prospectus and the
documents incorporated by reference in this prospectus. If any of the events
described below occur, our business, financial condition and/or results of
operations could be materially harmed, and you could lose part or all of your
investment.

                                        1


Risks Relating to Our Business

Our business activities are subject to hazards and risks. The following is a
summary of some of the material risks relating to our business activities. You
should also read the information set forth under the caption "Cautionary
Statement for Purposes of the 'Safe Harbor' Provisions of the Private Securities
Litigation Reform Act of 1995" on pages 51 to 53 of our 2001 Annual Report on
Form 10-K.

Our Profitability Is Highly Dependent on the Prices of Crude Oil, Natural Gas
and Natural Gas Liquids, Which Have Historically Been Very Volatile.

Our revenues, profitability, cash flow and future rate of growth are highly
dependent on the prices of crude oil, natural gas and natural gas liquids, which
are affected by numerous factors beyond our control. Oil and gas liquids and gas
prices historically have been very volatile. For example, our lower 48 U.S. gas
prices declined significantly in 2001 from the very high levels reached in the
second half of 2000 and early 2001. A significant downward trend in commodity
prices, comparable to the commodity prices experienced in 1998, would have a
material adverse effect on our revenues, profitability and cash flow and could
result in a reduction in the carrying value of our oil and gas properties and
the amounts of our proved oil and gas reserves.

Our Hedging and Speculating Activities May Prevent Us from Benefiting from Price
Increases and May Expose Us to Other Risks.

To the extent that we engage in hedging activities to endeavor to protect
ourselves from price volatility, we may be prevented from realizing the benefits
of price increases above the levels of the hedges. In addition, we engage in
speculative trading in hydrocarbon commodities and derivative instruments in
connection with our risk management activities, which subjects us to additional
risk.

Our Drilling Activities May Not Be Productive.

Drilling for oil and gas involves numerous risks, including the risk that we
will not encounter commercially productive oil or gas reservoirs. The costs of
drilling, completing and operating wells are often uncertain and drilling
operations may be curtailed, delayed or canceled as a result of a variety of
factors, including:

o    Unexpected drilling conditions;
o    Pressure or irregularities in formations;
o    Equipment failures or accidents;
o    Fires, explosions, blow-outs and surface cratering;
o    Marine  risks  such as  capsizing,  collisions  and  hurricanes;  o Adverse
     weather conditions; and o Shortages or delays in the delivery of equipment.

                                        2


Our future drilling activities may not be successful and, if unsuccessful, this
failure could have an adverse effect on our future results of operations and
financial condition. While all drilling, whether developmental or exploratory,
involves these risks, exploratory drilling involves greater risks of dry holes
or failure to find commercial quantities of hydrocarbons. Because of the
percentage of our capital budget devoted to higher risk exploratory projects, it
is likely that we will continue to experience significant exploration and dry
hole expenses.

As part of our strategy, we explore for oil and gas offshore, sometimes in deep
water or at deep drilling depths, where operations are more difficult and costly
than on land or than at shallower depths and in shallower waters. Deep- water
operations may require a significant amount of time between a discovery and the
time that we can market the oil or gas, increasing both the financial and
operational risk involved with these activities.

Operating Risks

Our business is subject to all of the operating risks normally associated with
the exploration for and production of oil and gas, including blowouts, cratering
and fire, any of which could result in damage to, or destruction of, oil and gas
wells or formations or production facilities and other property and injury to
persons. As protection against financial loss resulting from these operating
hazards, we maintain insurance coverage, including certain physical damage,
comprehensive general liability and worker's compensation insurance. Although we
are not fully insured against all risks in our business, we believe that the
coverage we maintain is customary for companies engaged in similar operations.
The occurrence of a significant event against which we are not fully insured
could have a material adverse effect on our results of operations and possibly
on our financial position.

Development Risks

We are involved in several large development projects, principally offshore. Key
factors that may affect the timing and outcome of such projects include: project
approvals by joint venture partners; timely issuance of permits and licenses by
governmental agencies; manufacturing and delivery schedules of critical
equipment, such as offshore platforms, and commercial arrangements for pipelines
and related equipment to transport and market hydrocarbons. In our experience
with such large development projects, these uncertainties are usually resolved,
but delays and differences between estimated and actual timing of critical
events may affect the completion of and commencement of production from
projects.

Our Oil and Gas Reserve Data and Future Net Revenue Estimates Are Uncertain.

Estimates of reserves by necessity are projections based on engineering data,
the projection of future rates of production and the timing of future
expenditures. We base the estimates of our proved oil and gas reserves and
projected future net revenues on reserve reports we prepare. The process of
estimating oil and gas reserves requires substantial judgment on the part of the
petroleum engineers, resulting in imprecise determinations, particularly with
respect to new discoveries. Different reserve engineers may make different
estimates of reserve quantities and

                                       3


revenues attributable to those reserves based on the same data. Future
performance that deviates significantly from reserve reports could have a
material adverse effect on our business and prospects, as well as on the amounts
and carrying values of such reserves.

Fluctuations in the price of oil and natural gas have the effect of
significantly altering reserve estimates, because the economic projections
inherent in the estimates may reduce or increase the quantities of recoverable
reserves. We may not realize the prices our reserve estimates reflect or produce
the estimated volumes during the periods those estimates reflect. Actual future
production, oil and natural gas prices, revenues, taxes, development
expenditures, operating expenses and quantities of recoverable oil and natural
gas reserves most likely will vary from our estimates.

Any downward revision in our estimated quantities of reserves or of the carrying
values of our reserves could have adverse consequences on our financial results,
such as increased depreciation, depletion and amortization charges and/or
impairment charges, which would reduce earnings and stockholders' equity.

If We Fail to Find or Acquire Additional Reserves, Our Reserves and Production
Will Decline Materially from Their Current Levels.

The rate of production from oil and gas properties generally declines as
reserves are depleted. Except to the extent we conduct successful exploration
and development activities or, through engineering studies, identify additional
productive zones or secondary recovery reserves, and/or acquire additional
properties containing proved reserves, our proved reserves will decline
materially as oil and gas is produced. Future oil and gas production is,
therefore, highly dependent on our level of success in finding or acquiring
additional reserves.

Our Growth Depends Significantly on Our Ability to Acquire Oil and Gas
Properties on a Profitable Basis.

Acquisitions of producing oil and gas properties have been a key element of
maintaining and growing our reserves and production in recent years,
particularly in North America. The success of any acquisition will depend on a
number of factors, including the ability to estimate accurately the recoverable
volumes of reserves, rates of future production and future net revenues
attainable from reserves and to assess future abandonment and possible future
environmental liabilities.

There are numerous uncertainties inherent in estimating quantities of proved oil
and gas reserves and actual future production rates and associated costs with
respect to acquired properties. Actual results may vary substantially from those
assumed in the estimates.

Domestic Governmental Risks

Our domestic operations have been, and at times in the future may be, affected
by political developments and by federal, state and local laws and regulations
such as restrictions on

                                        4


production, changes in taxes, royalties and other amounts payable to governments
or governmental agencies, price controls and environmental protection
regulations.

Global Political and Economic Developments May Impact Operations.

Political and economic factors in international markets may have a material
adverse effect on our operations. On an equivalent-barrel basis, approximately
one-half of our oil and gas production in 2001 was outside the United States,
and approximately two-thirds of our proved oil and gas reserves at December 31,
2001, were located outside of the United States. All of our geothermal
operations and reserves are located outside the United States.

There are many risks associated with operations in international markets,
including changes in foreign governmental policies relating to crude oil,
natural gas liquids, natural gas and geothermal steam pricing and taxation,
other political, economic or diplomatic developments, changing political
conditions and international monetary fluctuations. These risks include:

o    Political and economic instability or war;
o    The  possibility  that a foreign  government may seize our property with or
     without compensation;
o    Confiscatory taxation;
o    A  foreign   government   attempting  to  renegotiate  or  revoke  existing
     contractual arrangements;
o    Fluctuating currency values and currency controls; and
o    Constrained natural gas markets dependent on demand in a single or limited
     geographical area.

Actions of the United States government through tax and other legislation,
executive order and commercial restrictions can adversely affect our operating
profitability overseas, as well as in the U.S. The United States government can
prevent or restrict us from doing business in foreign countries. These
restrictions and those of foreign governments have in the past limited our
ability to operate in or gain access to opportunities in various countries.
Various agencies of the United States and other governments have from time to
time imposed restrictions on our ability to operate in or gain attractive
opportunities in various countries. Actions by both the United States and host
governments have affected operations significantly in the past and will continue
to do so in the future.

The Oil and Gas Exploration and Production Industry Is Very Competitive, and
Many of Our Exploration and Production Competitors Have Greater Financial and/or
Other Resources than We Do.

Strong competition exists in all sectors of the oil and gas exploration and
production industry and, in particular, in the exploration and development of
new reserves. We compete with major integrated and other independent oil and gas
companies for the acquisition of oil and gas leases and other properties, for
the equipment and labor required to develop and operate those properties and the
marketing of oil and natural gas production. Many of our competitors have
financial and other resources substantially greater than those available to us.
As a  consequence,

                                        5


  we may be at a competitive disadvantage in bidding for drilling rights. In
addition, many of our larger competitors may have a competitive advantage when
responding to factors that affect the demand for oil and natural gas production,
such as changes in worldwide prices and levels of production, the cost and
availability of alternative fuels and the application of government regulations.
We also compete in attracting and retaining personnel, including geologists,
geophysicists, engineers and other specialists.

Environmental Compliance and Remediation Have Resulted in and Could Continue to
Result in Increased Capital Requirements and Operating Costs.

Our operations are subject to numerous laws and regulations relating to the
protection of the environment. We have incurred and will continue to incur
substantial capital, operating and maintenance, and remediation expenditures as
a result of these laws and regulations. Our compliance with amended, new or more
stringent requirements, stricter interpretations of existing requirements or the
future discovery of contamination may require us to make material expenditures
or subject us to liabilities beyond what we currently anticipate. In addition,
any failure by us to comply with existing or future laws could result in civil
or criminal fines and other enforcement action against us.

Our past and present operations and those of companies we have acquired expose
us to civil claims by third parties for alleged liability resulting from
contamination of the environment or personal injuries caused by releases of
hazardous substances.

For example:

o    We are investigating or remediating contamination at a large number of
     formerly and currently owned and/or operated sites; and
o    We have been identified as a potentially responsible party at several
     Superfund and other multi-party sites where we or our predecessors are
     alleged to have disposed of wastes in the past.

Environmental laws are subject to frequent change and many of them have become
more stringent. In some cases, they can impose liability for the entire cost of
cleanup on any responsible party without regard to negligence or fault and
impose liability on us for the conduct of others or conditions others have
caused, or for our acts that complied with all applicable requirements when we
performed them.

It is not possible for us to estimate reliably the amount and timing of all
future expenditures related to environmental and legal matters and other
contingencies because:

o    Some sites are in the early stages of investigation, and other sites may be
     identified in the future;
o    Cleanup requirements are difficult to predict at sites where remedial
     investigations have not been completed or final decisions have not been
     made regarding cleanup requirements, technologies or other fators that bear
     on cleanup costs;
                                        6



o    Environmental laws frequently impose joint and several liability on all
     potentially responsible parties, and it can be difficult to determine the
     number and financial condition of other potentially responsible parties and
     their shares of responsibility for cleanup costs;
o    Environmental  laws and  regulations are  continually  changing,  and court
     proceedings are inherently uncertain; and
o    Some legal matters are in the early stages of investigation or proceeding
     or their outcomes otherwise may be difficult to predict, and other legal
     matters may be identified in the future.


Although our management believes that it has established appropriate reserves
for cleanup costs, due to these uncertainties we could be required to provide
significant additional reserves in the future, which would adversely affect our
results of operations and possibly our financial position.

Unocal Depends Upon Payments from Its Subsidiaries.

Unocal conducts substantially all of its operations through Union Oil,
65-percent-owned Pure Resources, Inc., and other subsidiaries. Unocal's
principal sources of cash are dividends and advances from its subsidiaries,
investments, payments by subsidiaries for services rendered and interest
payments from subsidiaries on cash advances. The amount of cash and income
available to Unocal from its subsidiaries largely depends upon each subsidiary's
earnings and operating capital requirements. The terms of Pure's borrowing
arrangements and its publicly-held minority interest limit payments and
transfers of funds. In addition, the ability of the subsidiaries to make any
payments or transfer funds will depend on the subsidiaries' earnings, business
and tax considerations and legal restrictions. Failure to receive adequate cash
and income from its subsidiaries could jeopardize Unocal's ability to make
payments on debt securities issued by Unocal, including those held by Unocal
Capital Trust, to satisfy Unocal's guarantees of debt securities of Union Oil
and the preferred securities of Unocal Capital Trust, and to pay dividends on
its common stock.

Our Debt Level May Limit Our Financial Flexibility.

As of March 31, 2002, we had approximately $3.2 billion of total debt
outstanding and a total-debt-to-total-capital ratio of 47 percent. In addition,
Unocal Capital Trust has $522 million of convertible preferred securities
outstanding, which represent beneficial interests in a like amount of
subordinated debt issued to the Trust by Unocal. We have incurred additional
debt since March 31st and may also incur additional debt in the future,
including in connection with acquisitions. The level of our debt could have
several important effects on our future operations, including, among others:

o    A significant portion of our cash flow from operations will be applied to
     the payment of principal and interest on the debt and will not be available
     for other purposes;
o    Credit rating agencies have and may continue to change our debt ratings as
     a result of changes in our debt level, financial condition, earnings and
     cash flow, which in turn impact the costs, terms and conditions and
     availability of financing;

                                        7


o    Covenants contained in our existing and future debt arrangements will
     require us to meet financial tests that may affect our flexibility in
     planning for and reacting to changes in its business, including possible
     acquisition opportunities;
o    Our ability to obtain additional financing for working capital, capital
     expenditures, acquisitions, general corporate and other purposes may be
     limited or burdened by increased costs or more restrictive covenants;
o    We may be at a competitive disadvantage to similar companies that have less
     debt; and
o    Our vulnerability to adverse economic and industry conditions may increase.

A Change of Control of Unocal Could Result in the Acceleration of Our
Outstanding Bank Borrowings and Trigger Various Change-of-Control Provisions
Included in Employee and Director Plans and Agreements.

Two of our bank credit facilities, under which we can borrow up to
$1,000,000,000, provide for the termination of their loan commitments and
require the prepayment of all outstanding borrowings under the facilities in the
event that (1) any person or group becomes the beneficial owner of more than 30
percent of the then outstanding voting stock of Unocal other than in a
transaction having the approval of Unocal's board of directors, at least a
majority of which are continuing directors, or (2) if continuing directors shall
cease to constitute at least a majority of the board. If this situation were to
occur, we would likely be required to refinance the outstanding indebtedness
under these credit facilities. There can be no assurance that we would be able
to refinance this indebtedness or, if a refinancing were to occur, that the
refinancing would be on terms favorable to us.

Under various employee and director plans and agreements, in the event of a
change in control, restricted stock would become unrestricted, unvested options
and phantom units would vest, performance shares, performance bonus awards and
incentive compensation would be paid out, and directors' units would be paid out
if the director has so elected. We have also entered into employment agreements
and other agreements with certain of our employees containing change-of-control
provisions.

We have adopted an enhanced severance program for approximately 2,800
U.S-payroll employees not represented by collective bargaining agreements and a
limited number of international employees in the event they lose their jobs
through a change of control.

In the event of a change of control of either Unocal or the Company's Pure
subsidiary, as well as under certain circumstances specified in the employment
and/or severance agreements entered into between Pure and certain of its
officers, each covered officer will have the right to require Pure to purchase
its common shares currently held or subsequently obtained by the exercise of any
option held by the officer at a calculated "net asset value" per Pure share,
determined as provided in the agreements. At March 31, 2002, Pure estimated that
the repurchase obligation under these agreements, if triggered, was
approximately $69 million.

                                        8



Unocal May Issue Preferred Stock, the Terms of Which Could Adversely Affect the
Voting Power or Value of Its Common Stock.

Unocal's Restated Certificate of Incorporation authorizes it to issue, upon
approval of its board of directors, but without the approval of its
stockholders, one or more classes or series of preferred stock having such
preferences, powers and relative, participating, optional and other rights,
including preferences over its common stock respecting dividends and
distributions, as its board of directors generally may determine. The terms of
one or more classes or series of preferred stock could adversely impact the
voting power or value of Unocal's common stock. For example, Unocal might grant
holders of preferred stock the right to elect some number of its directors in
all events or on the happening of specified events or the right to veto
specified transactions. Similarly, the repurchase or redemption rights or
liquidation preferences Unocal might assign to holders of preferred stock could
affect the residual value of the common stock.

Provisions in Unocal's Corporate Documents and Delaware Law Could Delay or
Prevent a Change of Control of Unocal, Even If That Change Would Be Beneficial
to Its Stockholders.

The existence of some provisions in Unocal's corporate documents and Delaware
law could delay or prevent a change of control of Unocal, even if that change
would be beneficial to its stockholders. Unocal's Restated Certificate of
Incorporation and Bylaws contain provisions that may make acquiring control of
Unocal difficult, including:

o    Provisions  relating  to the  classification,  nomination  and  removal  of
     directors;
o    A provision prohibiting stockholder action by written consent;
o    A provision that allows only its board of directors to call a special
     meeting of its stockholders;
o    Provisions regulating the ability of its stockholders to bring matters for
     action before annual meetings of its stockholders; and
o    The authorization given to its board of directors to issue and set the
     terms of preferred stock.

In addition, Unocal has also adopted a stockholder rights plan, which would
cause extreme dilution to any person or group that attempts to acquire a
significant interest in Unocal without advance approval of its board of
directors, while a provision of the Delaware General Corporation Law would
impose some restrictions on mergers and other business combinations between
Unocal and any holder of 15 percent or more of its outstanding common stock.

Unocal May Reduce or Cease to Pay Dividends on Its Common Stock.

Unocal's stockholders may receive reduced or no future dividends. The amount of
cash dividends, if any, to be paid in the future will depend upon their
declaration by Unocal's board of directors and upon Unocal's financial
condition, results of operations, cash flow, the level of its capital and
exploration expenditures, its future business prospects and other related
matters that Unocal's board of directors deems relevant.


                                        9



In addition, under the terms of the outstanding preferred securities of Unocal
Capital Trust and the Unocal subordinated debt securities held by the Trust, in
which the trust preferred securities represent beneficial interests, Unocal has
the right, under certain circumstances to suspend the payment to the Trust of
interest on the debt securities, in which event the Trust has the right to
suspend the payment of distributions on the trust preferred securities. In this
situation, Unocal would be prohibited from paying dividends on the common stock.

                                 USE OF PROCEEDS

The shares covered by this Prospectus will be sold by the Selling Stockholders
as principals for their own account. The Company will not receive any proceeds
from sales of any such shares.

                              SELLING STOCKHOLDERS

This Prospectus relates to shares of common stock (including the associated
preferred stock purchase rights) that have been acquired by the Selling
Stockholders pursuant to our Executive Stock Purchase Plan which was approved by
stockholders in 2000. Six of the Selling Stockholders are employees of Union Oil
or one of its subsidiaries; the other three are former employees. The following
table sets forth: (a) the name and positions over the past three years with the
company of each Selling Stockholder; (b) the number of shares of common stock
each Selling Stockholder beneficially owned as of June 28, 2002; (c) the number
of shares of common stock acquired by each Selling Stockholder pursuant to the
plan and being registered for resale under this Registration Statement, some or
all of which shares may be sold pursuant to this Prospectus; and (d) the number
of shares of common stock of the total class of common stock outstanding to be
beneficially owned by each Selling Stockholder following this offering, assuming
the sale pursuant to this offering of all shares acquired by such Selling
Stockholder pursuant to the plan and registered under this Registration
Statement. There is no assurance that any of the Selling Stockholders will sell
any or all of the shares offered in this Registration Statement.

                                                                                          

----------------------------------------------------------------------------------------------------------------------
       Name                 No. of
                            Shares       No. of                                                        No. of Shares
                            Before       Resale        Principal Positions with                           After
                            Offering     Shares        Company for Last 3 Years                         Offering(1)
----------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------
Charles R. Williamson       220,300      179,736       Chairman of the Board since October 2001 and        40,564
                                                       Chief Executive Officer since January 2001;
                                                       previously, Executive Vice President,
                                                       International Energy Operations, during 1999
                                                       and 2000, Group Vice President, Asia
                                                       Operations, in 1998 and 1999, Group Vice
                                                       President, International Operations, since
                                                       1996
----------------------------------------------------------------------------------------------------------------------

                                       10


----------------------------------------------------------------------------------------------------------------------
Timothy H. Ling              233,252     179,736       President and Chief Operating Officer since         53,516
                                                       January 2001; previously, Executive Vice
                                                       President, North American Energy Operations,
                                                       in 1999 and 2000, and Chief Financial Officer
                                                       from 1997 to 2000; also a director of Pure
                                                       Resources, Inc.
----------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------
Dennis P.R. Codon            122,574      89,868       Senior Vice President, Chief Legal Officer          32,706
                                                       and General Counsel since August 2000;
                                                       previously, Vice President, Chief Legal
                                                       Officer and General Counsel since 1992.
----------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------
Randy L. Howard              114,627      89,868       Vice President, International Energy                24,759
                                                       Operations--Myanmar, Thailand, Vietnam, since
                                                       June 1999; previously Group Vice President,
                                                       International Operations, Geothermal, since
                                                       1998, and Vice President, Geothermal
                                                       Operations, since 1997
----------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------
Andrew L. Fawthrop            98,352      89,868       Vice President, International Energy                 8,484
                                                       Operations--West Africa, Latin America,
                                                       Caspian and Europe, since March 1999;
                                                       previously New Ventures Vice President, West
                                                       Caspian/ Middle East, since 1997
----------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------
Brian W.G. Marcotte          108,768      71,894       Vice President, International Energy                36,874
                                                       Operations--Brunei, Indonesia, Philippines,
                                                       since June 1999; previously President, Unocal
                                                       Thailand Ltd. since 1993
----------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------
R. Boyd Montgomery            4,089          800       No longer with the Company; formerly, Vice           3,289
                                                       President, International Energy
                                                       Operations--Bangladesh, China, India, since
                                                       March 1999; previously, New Ventures Vice
                                                       President, East Asia/South Asia, since 1997
----------------------------------------------------------------------------------------------------------------------

                                       11


----------------------------------------------------------------------------------------------------------------------
Roger C. Beach              271,228       179,736      No longer with the Company; formerly,
                                                       Chairman of the Board 1995-2000 and Chief
                                                       Executive Officer 1994-2000
----------------------------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------------------------
John T. Donohue               2,800           868      No longer with the Company; formerly,                1,932
                                                       President Sprit Energy 76 1999-2000,
                                                       and Vice President, Agricultural Products
                                                       1996-1999
----------------------------------------------------------------------------------------------------------------------
John C. Ellice-Flint        115,287        89,868      No longer with the Company; formerly, Senior        25,419
                                                       Vice President, Global Exploration and
                                                       Technology, since December 1997
----------------------------------------------------------------------------------------------------------------------


(1) Assuming Selling Stockholders sell all of their resale shares.



                              PLAN OF DISTRIBUTION

It is anticipated that the Selling Stockholders will offer some or all of their
shares for sale at prices prevailing on the New York Stock Exchange on the date
of sale. We will not receive any of the proceeds from the sale of the shares.
The Selling Stockholders will pay all selling and other expenses, if any,
associated with any sale of the shares. We will pay all of the expenses of
registration incurred in connection with this offering.

Each Selling Stockholder and any broker executing selling orders on behalf of
them may be deemed an "underwriter" within the meaning of the Securities Act of
1933, as amended, in which event commissions received by such broker may be
deemed to be underwriting commissions under the Securities Act.

                                  LEGAL MATTERS

Legal matters in connection with the issuance and sale of the securities offered
hereby will be passed upon by Dennis P.R. Codon, Esq., Senior Vice President,
Chief Legal Officer and General Counsel of the Company. As of June 28, 2002, Mr.
Codon owned beneficially 122,574 shares of Common Stock. He also held options to
purchase 212,218 shares of common stock at prices ranging from $32.8125 to
$38.8125, with expiration dates ranging from 2006 to 2011. In addition, Mr.
Codon held 19,500 performance share units, which could be paid out in up to
39,000 shares of common stock four years after their award dates, depending upon
our total return to stockholders.

                                       12




                                     EXPERTS

The financial statements incorporated in this Prospectus by reference to the
Annual Report on Form 10-K for the year ended December 31, 2001 have been so
incorporated in reliance on the report of PricewaterhouseCoopers LLP,
independent accountants, given on the authority of said firm as experts in
auditing and accounting.


                       WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and special reports, proxy statements and other
information with the Securities and Exchange Commission (the "SEC"). Our SEC
filings are available to the public over the Internet at the SEC's web site at
http://www.sec.gov. You may also read and copy any prospectus we file with the
SEC at the SEC's Public Reference Room at 450 Fifth Street, N.W., Washington,
D.C. 20549. Please call the SEC at 1-800-SEC-0330 for further information on the
SEC's public reference facilities.

We have filed a registration statement with the SEC on Form S-3 pursuant to the
Securities Act of 1933 for the shares of common stock offered by this
Prospectus. In accordance with the rules and regulations of the SEC, this
Prospectus does not contain all of the information set forth in the registration
statement. For further information regarding the shares of common stock offered
by this Prospectus, you may examine our registration statement and the documents
incorporated therein by reference without charge at the SEC's public reference
facilities identified above.

Our reports, proxy statements and other information can also be inspected and
copied at the offices of the New York Stock Exchange at 20 Broad Street, 17th
Floor, New York, New York 10005. Our common stock is listed on the New York
Stock Exchange.

The SEC allows us to incorporate by reference the information we file with the
SEC. This means that we can disclose important information to you by referring
you to the documents we file with the SEC. The information incorporated by
reference is an important part of this prospectus, and information that we file
later with the SEC will automatically update and supersede this information. We
incorporate by reference the documents listed below and any future filings made
with the SEC under Sections 13(a), 13(c), 14, or 15(d) of the Securities and
Exchange Act of 1934:

a.   Our Annual Report on Form 10-K for the fiscal year ended December 31, 2001;

b.   Our Quarterly Report on Form 10-Q for the fiscal year ended March 31, 2002;

c.   Our Current Reports on Form 8-K dated January 22 and 24, March 27,  April 8
     and 25, and June 20, 2002;

d.   All of our other  reports  filed  pursuant to Section 13(a) or 15(d) of the
     Securities  Exchange Act of 1934, as amended (the  "Exchange  Act"),  since
     December 31, 2001; and
                                       13




e.   The description of our Common Stock,  $1.00 par value per share,  excluding
     that of the associated Preferred Stock Purchase Rights, set forth under the
     caption "Description of the Common Stock," included in the prospectus dated
     September 25, 1998,  of Union Oil Company of  California  and us (File Nos.
     333-58415  and  333-58415-01),  together  with the  description  of our now
     associated  Preferred  Share Purchase Rights included in our Current Report
     on Form 8-K dated  January 5, 2000,  as they have been amended as set forth
     in our Current Report on Form 8-K dated March 27, 2002. The descriptions of
     the 6.25% Trust Convertible  Preferred  Securities of Unocal Capital Trust,
     (the "Trust Convertible  Preferred  Securities"),  the guarantee thereof by
     us, and our 6.25% Convertible Junior Subordinated Debentures (as the rights
     and terms of which may materially limit or qualify the rights evidenced by,
     or amounts  payable with respect to, our common  stock) set forth under the
     captions  "Description  of the  Trust  Convertible  Preferred  Securities,"
     "Description   of  the   Guarantee,"   "Description   of  the   Convertible
     Debentures,"  and "Effect of Obligations  under the Convertible  Debentures
     and the Guarantee" in the prospectus dated August 7, 1996,  included in the
     Registration Statement on Form S-4 of Unocal and Unocal Capital Trust (File
     Nos. 333-09137 and 333-09137-01), as amended by Pre-Effective Amendment No.
     1.

All documents filed by us pursuant to Sections 13(a), 13(c), 14 and 15(d) of the
Exchange Act prior to the filing of a post-effective amendment which indicates
that all securities offered have been sold or which deregisters all securities
then remaining unsold, shall be deemed to be incorporated by reference in this
Prospectus and to be a part hereof from the date of filing of such documents.

You may obtain copies of certain documents referred to above at our web site at
http://www.unocal.com. You also may obtain a copy of any such document at no
charge by writing or telephoning us at the following:

                         Stockholder Services Department
                               Unocal Corporation
                        2141 Rosecrans Avenue, Suite 4000
                          El Segundo, California 90245
                                 (800) 252-2233

                                       14



                PART II - INFORMATION NOT REQUIRED IN PROSPECTUS

Item 14.  Other Expenses of Issuance and Distribution.*

Securities and Exchange Commission registration fee              $     4,047
Accounting fees                                                       17,500
Printing, distribution, and engraving fees                                 0
Legal fees and expenses                                                    0
Miscellaneous                                                              0
                                                                ------------
Total                                                            $    21,547

*    All amounts are estimated except for the Securities and Exchange Commission
     registration fee.

Item 15.  Indemnification of Directors and Officers.

Section 145 of the Delaware General Corporation Law authorizes Unocal to
indemnify directors and officers in certain circumstances against liabilities,
including expenses, incurred while acting in such capacities; provided,
generally, that any such indemnified director or officer acted in good faith and
in a manner he or she reasonably believed to be in the best interests of the
corporation and, in the case of a criminal proceeding, had no reasonable cause
to believe his or her conduct was unlawful. The Bylaws of Unocal provide for the
indemnification of directors and officers to the maximum extent permitted by the
Delaware General Corporation Law.

In addition, Unocal has provided in its Restated Certificate of Incorporation
that it shall eliminate the personal liability of its directors to the fullest
extent permitted by the Delaware General Corporation Law and Unocal has entered
into indemnification agreements with each of its directors and officers
providing for additional indemnification. Unocal has policies of directors' and
officers' liability insurance which insure directors and officers against the
costs of defense, settlement or payment of a judgment under certain
circumstances.

Item 16.  Exhibits.

The Exhibit Index lists the exhibits that are filed as part of this registration
statement.

Item 17.  Undertakings.

a.   The undersigned Registrant hereby undertakes:

     1.   To file, during any period in which offers or sales are being made, a
          post-effective amendment to this registration statement:

          a.   To include any  prospectus  required by  Section 10(a)(3)  of the
               Securities Act of 1933, as amended (the "Securities Act");

          b.   To reflect in the  prospectus  any facts or events  arising after
               the effective  date of this  registration  statement (or the most
               recent post-effective amendment thereof)

                                       15



               which, individually or in the aggregate, represent a fundamental
               change in the information set forth in this registration
               statement. Notwithstanding the foregoing, any increase or
               decrease in volume of securities offered (if the total dollar
               value of securities offered would not exceed that which was
               registered) and any deviation from the low or high end of the
               estimated maximum offering range may be reflected in the form of
               prospectus filed with the Commission pursuant to Rule 424(b) if,
               in the aggregate, the changes in volume and price represent no
               more than a 20 percent change in the maximum aggregate offering
               price set forth in the calculation of Registration Fee table in
               the effective registration statement;

          c.   To include  any  material  information  with  respect to the plan
               distribution  not  previously  disclosed in this statement or any
               material  change  to  such   information  in  this   registration
               statement;

     2.   Provided, however, that the undertakings set forth in paragraphs (a)
          and (b) above do not apply if the information required to be included
          in a post-effective amendment by those paragraphs is contained in
          periodic reports filed with the Commission by the Registrant pursuant
          to Section 13 or Section 15(d) of the Securities Act of 1934 (the
          "Exchange Act") that are incorporated by reference in this
          registration statement.

     3.   That, for the purpose of determining any liability under the
          Securities Act, each such post-effective amendment shall be deemed to
          be a new registration statement relating to the securities offered
          therein, and the offering of such securities at that time shall be
          deemed to be the initial bona fide offering thereof.

     4.   To remove from registration by means of a post-effective amendment,
          any of the securities being registered which remain unsold at the
          termination of the offering.

b.   The undersigned Registrant hereby undertakes that, for purposes of
     determining any liability under the Securities Act, each filing of the
     Registrant's annual report pursuant to Section 13(a) or Section 15(d) of
     the Exchange Act that is incorporated by reference in the registration
     statement shall be deemed to be a new registration statement relating to
     the securities offered therein, and the offering of such securities at that
     time shall be deemed to be the initial bona fide offering thereof.

c.   Insofar as indemnification for liabilities arising under the Securities Act
     may be permitted to  directors,  officers  and  controlling  persons of the
     Registrant  pursuant  to  the  foregoing  provisions,   or  otherwise,  the
     Registrant  has been  advised  that in the opinion of the  Commission  such
     indemnification  is against  public  policy as expressed in the Act and is,
     therefore,  unenforceable.  In the event  that a claim for  indemnification
     against  such  liabilities  (other  than the payment by the  Registrant  of
     expenses incurred or paid by a director,  officer or controlling  person of
     the Registrant in the successful defense of any action, suit or proceeding)
     is asserted by such director,  officer or controlling  person in connection
     with the securities being  registered,  the Registrant will,  unless in the
     opinion  of  its  counsel  the  matter  has  been  settled  by  controlling
     precedent,  submit  to a court of

                                       16


     appropriate jurisdiction the question whether such indemnification by it is
     against public policy as expressed in the Act and will be governed by the
     final adjudication of such issue.

                                   SIGNATURES

     Pursuant to the requirements of the Securities Act of 1933, the Registrant
     certifies that it has reasonable grounds to believe that it meets all of
     the requirements for filing on Form S-3 and has duly caused this
     registration statement to be signed on its behalf by the undersigned,
     thereunto duly authorized, in the City of El Segundo, State of California,
     on June 28, 2002.

                                                   UNOCAL CORPORATION


                                                  By /S/ Joe D. Cecil
                                                     ----------------
                                                  Joe D. Cecil
                                                  Vice President and Comptroller

Pursuant to the requirements of the Securities Act of 1933, this registration
statement has been signed by the following persons in the capacities and on the
date indicated:

                                                                                         

                SIGNATURE                                     TITLE                                 DATE

        /S/ Charles R. Williamson *             Chairman of the Board of Directors             June 28, 2002
        ---------------------------                 and Chief Executive Officer
          Charles R. Williamson                   (Principal Executive Officer)

                                                President, Chief Operating Officer             June 28, 2002
        ---------------------------                        and Director
             Timothy H. Ling

        /S/ Terry G. Dallas *                        Executive Vice President                  June 28, 2002
        ---------------------------                and Chief Financial Officer
             Terry G. Dallas

        /S/ Joe D. Cecil                          Vice President and Comptroller               June 28, 2002
        ---------------------------               (Principal Accounting Officer)
              Joe D. Cecil

                                                             Director                          June 28, 2002
        ---------------------------
             John W. Amerman


       /S/ John W. Creighton, Jr. *                          Director                          June 28, 2002
       ----------------------------
         John W. Creighton, Jr.


       /S/ James W. Crownover *                              Director                          June 28, 2002
       ----------------------------
           James W. Crownover


                                       17


        /S/ Frank C. Herringer *                             Director                          June 28, 2002
        --------------------------
           Frank C. Herringer
                                                             Director                          June 28, 2002
        --------------------------
            Charles R. Larson

        /S/ Donald B. Rice *                                 Director                          June 28, 2002
        --------------------------
             Donald B. Rice

        /S/ Kevin W. Sharer *                                Director                          June 28, 2002
        --------------------------
             Kevin W. Sharer

        /S/ Marina v.N. Whitman *
        --------------------------                           Director                          June 28, 2002
           Marina v.N. Whitman


       * By /S/ Joe D. Cecil
        --------------------------
        Joe D. Cecil
        Attorney-in-Fact

                                       18





                                  EXHIBIT INDEX
EXHIBIT
NUMBER                                             EXHIBIT

4.1  Restated Certificate of Incorporation of Unocal, dated as of January 31,
     2000, and currently in effect (incorporated by reference to Exhibit 3.1 to
     Unocal's Annual Report on Form 10-K for the year ended December 31, 1999,
     File No. 1-8483). *

4.2  Bylaws of Unocal, as amended through October 31, 2001, and currently in
     effect (incorporated by reference to Exhibit 3 to Unocal's Quarterly Report
     on Form 10-Q for the quarter ended September 30, 2001, File No. 1-8483). *

4.3  Rights Agreement, dated as of January 5, 2000, between Unocal and Mellon
     Investor Services, L.L.C., as Rights Agent (incorporated by reference to
     Exhibit 4 to Unocal's Current Report on Form 8-K dated January 5, 2000,
     File No. 1-8483), as amended by Amendment to Rights Agreement, dated as of
     March 27, 2002 (incorporated by reference to Exhibit 10 to Unocal's Current
     Report on Form 8-K dated March 27, 2002, File No. 1-8483). *

5    Opinion of Dennis P.R.  Codon,  Esq.,  Senior Vice  President,  Chief Legal
     Officer and General Counsel of Unocal.

23.1 Consent of PricewaterhouseCoopers LLP. *

23.2 Consent of Dennis P.R.  Codon,  Esq.,  Senior Vice  President,  Chief Legal
     Officer and General Counsel of Unocal (included in Exhibit 5).

24   Power of Attorney *


------------------------
*Previously filed.

                                       19