AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON NOVEMBER 21, 2001

                                                      REGISTRATION NO. 333-66472

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                         POST-EFFECTIVE AMENDMENT NO. 1
                                       TO
                                    FORM S-4
                                       ON
                                    FORM S-8
                             REGISTRATION STATEMENT
                                      UNDER
                           THE SECURITIES ACT OF 1933

                                NBT BANCORP INC.
                                ----------------
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

           DELAWARE                                     16-1268674
           --------                                     ----------
(STATE OR OTHER JURISDICTION OF             (I.R.S. EMPLOYER IDENTIFICATION NO.)
 INCORPORATION OR ORGANIZATION)

                 52 SOUTH BROAD STREET, NORWICH, NEW YORK 13815
                 ----------------------------------------------
               (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES) (ZIP CODE)

                 CNB FINANCIAL CORP. INCENTIVE STOCK OPTION PLAN
                         AS ASSUMED BY NBT BANCORP INC.
                         ------------------------------
                            (FULL TITLE OF THE PLAN)

                                DARYL R. FORSYTHE
                      PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                NBT BANCORP INC.
          52 SOUTH BROAD STREET, NORWICH, NEW YORK 13815 (607) 337-2265
          -------------------------------------------------------------
            (NAME, ADDRESS AND TELEPHONE NUMBER OF AGENT FOR SERVICE)

                                    COPY TO:
                              BRIAN D. ALPRIN, ESQ.
                             LAURENCE S. LESE, ESQ.
                          DUANE, MORRIS & HECKSCHER LLP
                         1667 K STREET, N.W., SUITE 700
                             WASHINGTON, D.C. 20006
                                 (202) 776-7800

          AN INDEX TO EXHIBITS IS INCLUDED ON PAGE 8 OF THIS FORM S-8.







         This post-effective amendment relates to 332,675 shares of NBT Bancorp
Inc. common stock into which were converted the 277,229 shares of CNB Financial
Corp. common stock that are subject to the CNB Incentive Stock Option Plan. NBT
assumed the CNB plan in accordance with the Agreement and Plan of Merger, dated
June 19, 2001, among NBT, NBT Bank, N.A., CNB and Central National Bank,
Canajoharie, upon completion of their merger on November 8, 2001. Upon
completion of the merger, the options to purchase 277,229 shares of CNB common
stock were converted into options to purchase 332,675 shares of NBT common
stock. The shares of NBT common stock issuable upon exercise of the former CNB
stock options under the CNB plan as assumed by NBT upon completion of the merger
were registered on the NBT Form S-4 registration statement to which this
post-effective amendment relates.


                                       2






PART I - INFORMATION REQUIRED IN THE SECTION 10(a) PROSPECTUS

         Pursuant to the note to Form S-8, the document containing the
information specified in Items 1 and 2 of Part I of the Form S-8 is not being
filed with the Commission as part of this Registration Statement, but will be
sent or given to participants as specified by Rule 428(b)(1).

PART II - INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 3 - Incorporation of Certain Documents by Reference
--------------------------------------------------------

         The following documents and portions of documents filed by NBT Bancorp
Inc. ("Bancorp") with the Commission are hereby incorporated into this
Registration Statement by reference:

           (a)  Bancorp's Annual Report on Form 10-K for the year ended December
                31, 2000;

           (b)  Bancorp's Quarterly Reports on Form 10-Q for the quarters ended
                March 31, 2001, June 30, 2001 and September 30, 2001;

           (c)  Bancorp's Current Reports on Form 8-K filed on January 3, 2001,
                June 5, 2001, June 22, 2001, July 27, 2001 and November 13,
                2001;

           (d)  (i)     Bancorp's Form 8-A/A filed with the SEC on May 9, 2000;

                (ii)    Bancorp's Form 8-A/A filed with the SEC on February 24,
                2000;

                (iii)   The description of Bancorp's Common Stock as set forth
                under the caption "DESCRIPTION OF NBT CAPITAL STOCK" presented
                in the prospectus portion of NBT's Form S-4 Registration
                Statement, SEC File No. 333-66472, filed with the Commission on
                August 1, 2001 and NBT's SEC Rule 424(b)(3) prospectus filed
                with the Commission on September 10, 2001.

         Bancorp additionally incorporates by reference herein all documents to
be subsequently filed by Bancorp pursuant to Sections 13(a), 13(c), 14 or 15(d)
of the Securities Exchange Act of 1934, as amended, prior to the filing of a
post-effective amendment which indicates that all the securities offered have
been sold or which deregisters all securities then remaining unsold, and deems
such documents to be incorporated by reference into this Registration Statement
and to be part of this Registration Statement from the dates of filing such
documents. Copies of these documents will not be filed with this Registration
Statement. Any statement contained herein or in a document incorporated or
deemed to be incorporated by reference herein shall be deemed to be modified or
superseded for purposes of this Registration Statement to the extent that such
statement is modified or superseded by a subsequently filed document which also
is or is deemed to be incorporated by reference into this Registration
Statement. Any such statement so modified or superseded shall not be deemed to
constitute a part of this Registration Statement except as so modified or
superseded.


                                       3




Item 4 - Description of Securities
----------------------------------

         This Item is omitted because Bancorp's Common Stock is registered under
Section 12 of the Exchange Act.

Item 5 - Interests of Named Experts and Counsel
-----------------------------------------------

         Members of Duane, Morris & Heckscher LLP, counsel for Bancorp, own
shares of Bancorp common stock. The fair market value of this stock ownership
exceeds $50,000 but represents less than .1% of Bancorp's outstanding shares.
Under the regulations of the Commission, Duane, Morris & Heckscher LLP may be
deemed to have a substantial interest in Bancorp.

Item 6 - Indemnification of Directors and Officers
--------------------------------------------------

         Bancorp's bylaws contain provisions providing that Bancorp shall
indemnify any person who was or is a party or threatened to be made a party to
any action, suit or proceeding, whether civil, criminal, administrative or
investigative, by reason of the fact that he or she is or was a director or
officer of Bancorp, or is or was serving at the request of Bancorp as a director
of another corporation, partnership, joint venture, trust, or other enterprise,
to the maximum extent authorized by the Delaware General Corporation Law.

         Bancorp's Certificate of Incorporation provides that a director of
Bancorp shall not be personally liable to Bancorp or its stockholders for
monetary damages for breach of fiduciary duty as a director, except for
liability (1) for any breach of the director's duty of loyalty to Bancorp or its
stockholders; (2) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law; (3) under ss. 174 of the
Delaware General Corporation Law; or (4) for any transaction from which the
director derived an improper personal benefit.

Item 7 - Exemption from Registration Claimed
--------------------------------------------

         This Item is omitted because it is not applicable.

Item 8 - Exhibits
-----------------

         The exhibits to this registration statement are listed in the Exhibit
Index included elsewhere herein.

Item 9 - Undertakings
---------------------

RULE 415 OFFERING

         The undersigned hereby undertakes:

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

                  (i)  To include any prospectus required by section 10(a)(3)
                   of the Securities Act of 1933;

                  (ii) To reflect in the prospectus any facts or events arising
                  after the effective date of the registration statement (or the
                  most recent post-effective amendment thereof) which,
                  individually or in the aggregate, represent a fundamental
                  change in the information set forth in the registration
                  statement;

                                       4




                  (iii) To include any material information with respect to the
                  plan of distribution not previously disclosed in the
                  registration statement or any material change to such
                  information in the registration statement;

         provided, however, that paragraph (1)(i) and (1)(ii) shall not apply if
         the information required to be included in a post-effective amendment
         by those paragraphs is contained in periodic reports filed with or
         furnished to the Commission by the registrant pursuant to section 13 or
         section 15(d) of the Securities Exchange Act of 1934 that are
         incorporated by reference in the registration statement.

(2)      That, for the purpose of determining any liability under the Securities
         Act of 1933, 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.

(3)      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.

FILINGS INCORPORATING SUBSEQUENT EXCHANGE ACT DOCUMENTS BY REFERENCE

         The undersigned registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act of 1933, each filing of the
registrant's annual report pursuant to Section 13(a) or 15(d) of the Securities
Exchange Act of 1934 (and, where applicable, each filing of an employee benefit
plan's annual report pursuant to Section 15(d) of the Securities Exchange Act of
1934) 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.

INDEMNIFICATION OF DIRECTORS AND OFFICERS

         Insofar as indemnification for liabilities arising under the Securities
Act of 1933 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 Securities and Exchange
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 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.




                                       5




                                   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-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Norwich, State of New York, on the 19th day of
November, 2001.

                                           NBT BANCORP INC.


                                      By: /s/ Daryl R. Forsythe
                                          ---------------------
                                          Daryl R. Forsythe
                                          President, Chief Executive Officer
                                          and Chairman of the Board of Directors

         Pursuant to the requirements of the Securities Act of 1933, this
Registration Statement has been signed below by the following persons in the
capacities indicated.




         Signature                          Title                                   Date
         ---------                          -----                                   ----
                                                                         

/s/ Daryl R. Forsythe          President, Chief Executive Officer and          November 19, 2001
----------------------------   Chairman of the Board of Directors
Daryl R. Forsythe              (Principal Executive Officer)


/s/ Michael J. Chewens*        Executive Vice President and                    November 19, 2001
----------------------------   Financial and Accounting Officer)
Michael J. Chewens


/s/ J. Peter Chaplin*          Director                                        November 19, 2001
----------------------------
J. Peter Chaplin

/s/ Richard Chojnowski*        Director                                        November 19, 2001
----------------------------
Richard Chojnowski

/s/ Gene E. Goldenziel*        Director                                        November 19, 2001
----------------------------
Gene E. Goldenziel

/s/ Peter B. Gregory*          Director                                        November 19, 2001
----------------------------
Peter B. Gregory

/s/ William C. Gumble*         Director                                        November 19, 2001
----------------------------
William C. Gumble

/s/ Bruce D. Howe*             Director                                        November 19, 2001
----------------------------
Bruce D. Howe

/s/Andrew S. Kowalczyk, Jr.*   Director                                        November 19, 2001
----------------------------
Andrew S. Kowalczyk, Jr.

/s/ John C. Mitchell*          Director                                        November 19, 2001
----------------------------
John C. Mitchell

/s/ Joseph G. Nasser*          Director                                        November 19, 2001
----------------------------
Joseph G. Nasser




                                       6





                                                                         
/s/ William L. Owens*          Director                                        November 19, 2001
----------------------------
William L. Owens

/s/ Paul O. Stillman*          Director                                        November 19, 2001
----------------------------
Paul O. Stillman

*By: /s/ Daryl R. Forsythe
     -----------------------
         Daryl R. Forsythe, Attorney-in-Fact
         under Power of Attorney











                                       7



                                INDEX TO EXHIBITS

         The following documents are attached as exhibits to this Form S-8 or,
if annotated by the symbol *, are incorporated by reference as Exhibits to
previous filings of the Registrant with the Commission.

Exhibit
Number
------

5.1               Opinion of Duane, Morris & Heckscher LLP.

23.1              Consent of Duane, Morris & Heckscher LLP
                     (contained in their opinion filed as Exhibit 5.1).

23.2              Consent of KPMG LLP.

99.1              CNB Financial Corp. Incentive Stock Option Plan, as assumed by
                  NBT Bancorp Inc.







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