HUDSON TECHNOLOGIES INC /NY
FIRST AMENDMENT TO REGISTRATION RIGHTS AGREEMENT
<DOCUMENT>
<TYPE>EX-10.25
<SEQUENCE>4
<FILENAME>d25204_ex10-25.txt
<DESCRIPTION>FIRST AMENDMENT TO REGISTRATION RIGHTS AGREEMENT
<TEXT>

                                  Exhibit 10.25


                FIRST AMENDMENT TO REGISTRATION RIGHTS AGREEMENT
                        effective as of February 16, 2001

     This First Amendment (this "Amendment"), effective as of February 16, 2001,
to  the  REGISTRATION  RIGHTS  AGREEMENT,  dated  as  of  March  30,  1999  (the
"Registration Rights Agreement"),  among Hudson  Technologies,  Inc., a New York
corporation (the "Company"),  Fleming US Discovery Fund III, L.P. and Fleming US
Discovery Offshore Fund III, L.P. (collectively, the "Fleming Funds").


                              W I T N E S S E T H:
                               - - - - - - - - - -

     WHEREAS,  the Company and the Fleming Funds are parties to the Registration
Rights Agreement;

     WHEREAS,  pursuant to the Stock Purchase Agreements,  dated as of March 30,
1999,  between the Company  and each of the Fleming  Funds (the "Stock  Purchase
Agreements"),  the Fleming Funds purchased 65,000 shares of the Company's Series
A Convertible Preferred Stock, par value $.01 per share (the "Series A Preferred
Stock");

     WHEREAS,  the Company and the Fleming  Funds  entered  into Stock  Purchase
Agreements,   dated  as  of  February   16,  2001  (the  "2001  Stock   Purchase
Agreements"), whereby the Fleming Funds purchased 30,000 shares of the Company's
Series A Convertible Preferred Stock, par value $.01 per share; and

     WHEREAS, pursuant to Section 11.4 of the Registration Rights Agreement, the
Company and the Fleming  Funds desire to (a) amend the first  WHEREAS  clause in
the Registration  Rights  Agreement to include the shares purchased  pursuant to
the 2001 Stock Purchase  Agreements,  (b) amend the second WHEREAS clause in the
Registration  Rights  Agreement  to  reflect  the  inclusion  of the 2001  Stock
Purchase Agreements and (c) amend the definition of "Stock Purchase  Agreements"
in the  Registration  Rights  Agreement  to  include  the  2001  Stock  Purchase
Agreements;

     NOW, THEREFORE,  in consideration of the foregoing and of the covenants and
agreements contained herein and for other good and valuable  consideration,  the
receipt of which is hereby  acknowledged,  the parties  hereto  hereby  agree as
follows:

     1. Capitalized  terms used but not otherwise  defined herein shall have the
respective meanings set forth in the Registration Rights Agreement.  Capitalized
terms  defined  in  this  Amendment  shall  be  deemed  to  be  defined  in  the
Registration  Rights  Agreement  with the meaning

<PAGE>

given to them herein. In the event of any inconsistency between the definitions,
terms or provisions of this Amendment and of the Registration  Rights Agreement,
this Amendment shall control.

     2. The first WHEREAS clause of the Registration  Rights Agreement is hereby
deleted and replaced in its entirety with the following:

     "WHEREAS,  pursuant to the terms of Stock Purchase Agreements,  dated as of
     March 30, 1999, and the Stock Purchase  Agreements,  dated as of February [
     ], 2001 (the "2001 Stock  Purchase  Agreements"),  the  Fleming  Funds have
     purchased 65,000 shares and 30,000 shares,  respectively,  of the Company's
     Series A Preferred Stock, par value $.01 per shares."

     3. The second WHEREAS clause of the Registration Rights Agreement is hereby
deleted and replaced in its entirety with the following:

     "WHEREAS,  (a) it was a condition of the  transactions  contemplated by the
     Stock  Purchase  Agreements  and (b) it is a condition to the  transactions
     contemplated  by the 2001 Stock Purchase  Agreements,  that the Company and
     Fleming enter into this Agreement  whereby the Company shall grant, and the
     Investors  shall obtain,  the rights  relating to the  registration  of the
     Registrable  Securities  under  the  Securities  Act,  as set forth in this
     Agreement;"

     4. The  definition of "Stock  Purchase  Agreements"  is hereby  deleted and
replaced in its entirety with the following:

     ""Stock  Purchase  Agreements"  means,  collectively,  the  separate  Stock
     Purchase  Agreements,  dated as of March 30, 1999,  between the Company and
     each of the Fleming Funds, and the 2001 Stock Purchase Agreements."

     5. Section  11.6(d)(ii) is hereby deleted and replaced in its entirety with
the following:

        "If to the Company, to:

        Hudson Technologies, Inc.
        275 North Middletown Road
        Pearl River, NY  10965
        Facsimile No.:  (914) 368-2540
        Attn:  Stephen P. Mandracchia


<PAGE>

        with a copy to:

        Blank Rome Tenzer Greenblatt LLP
        405 Lexington Avenue
        New York, NY  10174
        Facsimile No.:  (212) 885-5001
        Attn:  Ethan Seer, Esq.

     6. The Registration  Rights Agreement shall remain in full force and effect
in accordance with its terms, except as expressly amended hereby.

     7.  This  Amendment  may be  executed  in one or more  counterparts,  which
together will constitute a single agreement.

     8. This Amendment shall be governed by and construed in accordance with the
laws of the State of New York.

     9. This Amendment,  together with the Registration Rights Agreement and all
agreements or documents  herein or therein referred or incorporated by reference
contains  the entire  agreement  between the parties with respect to the subject
matter hereof and  supersedes any and all prior  agreements and  understandings,
oral or written, with respect to such subject matter.

                  [remainder of page intentionally left blank]

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     IN WITNESS WHEREOF, the parties have duly executed this Amendment as of the
date first written above.


                                   HUDSON TECHNOLOGIES, INC.


                                   By: /s/ Kevin J. Zugibe
                                       ------------------------------
                                       Name:
                                       Title:


                                   FLEMING US DISCOVERY FUND III, L.P.

                                   By: FLEMING US DISCOVERY
                                        PARTNERS, L.P.,
                                       its general partner

                                       By: FLEMING US DISCOVERY, LLC, its
                                           general partner


                                           By: /s/ Robert L. Burr
                                              ---------------------------------
                                                    Robert L. Burr, member



                                   FLEMING US DISCOVERY OFFSHORE
                                      FUND III, L.P.

                                   By:   FLEMING US DISCOVERY
                                            PARTNERS, L.P.,
                                         its general partner

                                         By: FLEMING US DISCOVERY, LLC,
                                             its general partner


                                                By: /s/ Robert L. Burr
                                                   ----------------------------
                                                     Robert L. Burr, member

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</DOCUMENT>
