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)
                                July 21, 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



         Total number of sequentially numbered pages in this filing,
                         including exhibits thereto:    6





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 filed herewith as Exhibit 99, which letter agreement
         was sent by Union Carbide to Dow Chemical on July 17, 2000 and
         executed by Dow Chemical on July 21, 2000.

Item 7.  FINANCIAL STATEMENTS AND EXHIBITS

         (c) Exhibits.

             99. Letter Agreement, 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:  July 24, 2000



                                        UNION CARBIDE CORPORATION





                                          /s/J. Macdonald
                                          J. Macdonald
                                          Assistant Secretary








                                      - 3 -



                                 EXHIBIT INDEX



Exhibits

99.   Letter Agreement, 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




                                                       July 17, 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 September 30, 2000.
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/ Bruce D. Fitzgerald
                                             Bruce D. Fitzgerald
                                             Vice President, General Counsel
                                               and Secretary


ACCEPTED AND AGREED as
of July 21, 2000:

THE DOW CHEMICAL COMPANY


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