FIRST AMENDMENT TO CREDIT AGREEMENT

                  FIRST   AMENDMENT,   dated  as  of  December  17,  1999  (this
"Amendment"), among HYDROCHEM HOLDING, INC., a Delaware corporation ("Holding"),
HYDROCHEM  INDUSTRIAL  SERVICES,  INC., a Delaware corporation (the "Borrower"),
the financial  institutions  party to the Credit Agreement  described below (the
"Lenders"),  and BANK OF AMERICA, N.A., as Administrative Agent. All capitalized
terms used herein and not  otherwise  defined  herein shall have the  respective
meanings provided such terms in the Credit Agreement referred to below.

                                   WITNESSETH:
                                   ----------

                  WHEREAS,   Holding,   the   Borrower,   the  Lenders  and  the
Administrative Agent are parties to a Credit Agreement, dated as of November 19,
1999 (the "Credit Agreement"); and

                  WHEREAS, the parties hereto wish to amend the Credit Agreement
as herein provided;

                  NOW THEREFORE, it is agreed:

I.                  First Amendment to Credit Agreement.
                    ------------------------------------

                  1. The Lenders  hereby agree (i) that Section  9.04(xi) of the
Credit Agreement is hereby amended by deleting the amount  "$500,000"  appearing
in the last line thereof and inserting the amount  "$1,000,000" in lieu thereof,
and  (ii)  that as of the  Amendment  Effective  Date  (as  defined  below)  the
foregoing  amendment to Section  9.04(xi) shall be deemed to have been effective
as of the Initial  Borrowing  Date and any Default or Event of Default  that has
arisen solely as a result of such  indebtedness  under Section 9.04(xi) being in
excess of $500,000 and less than or equal to $1,000,000 is hereby waived.

II.           Miscellaneous.
              --------------

                  1.  In  order  to  induce  the  Lenders  to  enter  into  this
Amendment,  each of Holding and the Borrower hereby represents and warrants that
(i) all representations, warranties and agreements contained in Section 7 of the
Credit Agreement are true and correct in all material  respects on and as of the
Amendment Effective Date (unless such representations and warranties relate to a
specific earlier date, in which case such  representations  and warranties shall
be true and correct in all material  respects as of such earlier  date) and (ii)
there exists no Default or Event of Default on the Amendment  Effective Date, in
each case after giving effect to this Amendment.


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                  2.  This  Amendment  is  limited  as  specified  and shall not
constitute a  modification,  acceptance or waiver of any other  provision of the
Credit Agreement or any other Credit Document.

                  3.  This   Amendment   may  be   executed  in  any  number  of
counterparts and by the different parties hereto on separate counterparts,  each
of  which  counterparts  when  executed  and  delivered  (including  by  way  of
facsimile) shall be an original,  but all of which shall together constitute one
and the same instrument. A complete set of counterparts shall be lodged with the
Borrower and the Administrative Agent.

                  4.  THIS  AMENDMENT  AND THE  RIGHTS  AND  OBLIGATIONS  OF THE
PARTIES  HEREUNDER SHALL BE CONSTRUED IN ACCORDANCE WITH AND GOVERNED BY THE LAW
OF THE STATE OF NEW YORK.

                  5. This  Amendment  shall  become  effective  on the date (the
"Amendment  Effective Date") when each of Holding, the Borrower and the Required
Lenders  shall have signed a counterpart  hereof  (whether the same or different
counterparts) and shall have delivered (including,  without limitation, by usage
of facsimile  transmission) the same to the  Administrative  Agent at the Notice
Office.  This Amendment and the agreements  contained herein shall be binding on
the successors and assigns of the parties hereto.

                  6. From and after the Amendment Effective Date, all references
in the  Credit  Agreement  and in  the  other  Credit  Documents  to the  Credit
Agreement  shall be deemed to be references to the Credit  Agreement as modified
hereby.

                                      * * *
                                        2


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                  IN WITNESS  WHEREOF,  each of the parties  hereto has caused a
counterpart  of this  Amendment to be duly executed and delivered as of the date
first above written.

                                       HYDROCHEM HOLDING, INC.

                                       By: /s/ Selby F. Little, III
                                       ----------------------------
                                       Name: Selby F. Little, III
                                       Title:Executive Vice President
                                             Chief Financial Officer


                                       HYDROCHEM INDUSTRIAL SERVICES, INC.

                                       By: /s/ Selby F. Little, III
                                       ----------------------------
                                       Name: Selby F. Little, III
                                       Title:Executive Vice President
                                             Chief Financial Officer


                                       BANK OF AMERICA, N.A.
                                        Individually and as Administrative Agent

                                       By: /s/ John J. ONeill
                                       ----------------------------
                                       Name: John J. ONeill
                                       Title:Managing Director


                                       WELLS FARGO BANK (TEXAS), NATIONAL
                                          ASSOCIATION

                                       By: /s/ Linda Masera
                                       ----------------------------
                                       Name: Linda Masera
                                       Title:Vice President


                                       NATEXIS BANQUE - BFCE

                                       By: /s/ Daniel Payer
                                       ----------------------------
                                       Name: Daniel Payer
                                       Title:Assistant Vice President

                                       By: /s/ Louis P. Laville, III
                                       ----------------------------
                                       Name: Louis P. Laville, III
                                       Title:Vice President and Group Manager


                                       NATIONAL CITY BANK OF KENTUCKY

                                       By: /s/ Tom Gurbach
                                       ----------------------------
                                       Name: Tom Gurbach
                                       Title:Vice President