8-K

                      SECURITIES AND EXCHANGE COMMISSION
                            Washington, D.C. 20549



                            ______________________

                                  FORM 8-K



                               CURRENT REPORT



                       Pursuant to Section 13 or 15(d) of
                      the Securities Exchange Act of 1934



                                 Date of Report
                       (Date of earliest event reported)
                                December 22, 2000



                           UNION CARBIDE CORPORATION
             (Exact name of registrant as specified in its charter)



    New York                     1-1463                       13-1421730
(State or other         (Commission File Number)             (IRS Employer
jurisdiction of                                           Identification No.)
incorporation)





              39 Old Ridgebury Rd, Danbury, CT           06817-0001
          (Address of principal executive offices)       (Zip code)



                        Registrant's telephone number,
                      including area code 203-794-2000








Item 5.  OTHER EVENTS


         With reference to the Agreement and Plan of Merger, dated as of
         August 3, 1999, among Union Carbide Corporation, a New York
         corporation ("Union Carbide"), The Dow Chemical Company, a Delaware
         corporation ("Dow Chemical"), and Transition Sub Inc., a Delaware
         corporation, Dow Chemical and Union Carbide have entered into a
         letter agreement, dated December 22, 2000 filed herewith as Exhibit 99.



Item 7.  FINANCIAL STATEMENTS AND EXHIBITS

         (c)  Exhibits.

              99. Letter Agreement, dated December 22, 2000, with reference
                  to the Agreement and Plan of Merger, dated as of August 3,
                  1999, among Union Carbide Corporation, a New York
                  corporation, The Dow Chemical Company, a Delaware
                  corporation, and Transition Sub Inc., a Delaware
                  corporation.






                                      - 2 -







Pursuant to the requirements of the Securities Exchange Act of 1934, the
Registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.




Date:  December 22, 2000



                                        UNION CARBIDE CORPORATION





                                        /s/J. Macdonald
                                        J. Macdonald
                                        Assistant Secretary




                                      - 3 -




                                 EXHIBIT INDEX



Exhibits

99.  Letter Agreement, dated December 22, 2000, with reference to the
     Agreement and Plan of Merger, dated as of August 3, 1999,
     among Union Carbide Corporation, a New York corporation, The Dow
     Chemical Company, a Delaware corporation, and Transition Sub Inc.,
     a Delaware corporation.





                                      - 4 -

EX-99

                                                       EXHIBIT 99






                                         December 22, 2000





VIA FAX AND OVERNIGHT MAIL



The Dow Chemical Company
2030 Dow Center
Midland, MI  48674

Attention:  Chief Executive Officer

Dear Sirs:

     Reference is made to the Agreement and Plan of Merger, dated as of August
3, 1999 (the "Agreement"), among Union Carbide Corporation, a New York
corporation, The Dow Chemical Company, a Delaware corporation, and Transition
Sub Inc., a Delaware corporation.

     Each of the parties hereto agrees that it will not exercise any right it
may have to terminate the Agreement under Section 8.2(i) of the Agreement
prior to March 31, 2001.  Notwithstanding anything to the contrary in the
foregoing, this letter agreement shall not in any way limit, restrict or
affect any of the other rights of the parties (relating to termination of the
Agreement or otherwise) under the Agreement.



                                  - 2 -

     If the foregoing is acceptable to you, please execute a copy of this
letter agreement in the space below, whereupon this instrument will constitute
a binding agreement among us.

                                    Very truly yours,

                                    UNION CARBIDE CORPORATION


                                    By:   /s/ B. D. Fitzgerald
                                          Name:   B.D. Fitzgerald
                                          Title:  Vice President,
                                          General Counsel and Secretary


ACCEPTED AND AGREED as
of the date first written above:

THE DOW CHEMICAL COMPANY


By:  /s/ J.P Reinhard
     Name:  J. P. Reinhard
     Title: Executive Vice President and
            Chief Financial Officer