ASSIGNMENT OF NOTES


                  HYDROCHEM  INDUSTRIAL  SERVICES,  INC., a Delaware corporation
hereinafter referred to as "Industrial  Services" located at 900 Georgia Avenue,
Deer Park,  Texas,  77536 for the sum of Two Hundred  Eighty-five  Thousand  Six
Hundred One and No/100 Dollars  ($285,601.00)  accrued interest in the amount of
Eleven  Thousand Nine Hundred Eight  Dollars and 39/100  ($11,908.39)  and other
good and valuable consideration, the receipt and sufficiency of which are hereby
acknowledged, has TRANSFERRED, SET-OVER and ASSIGNED, and by these presents does
TRANSFER,   SET-OVER  and  ASSIGN  unto  HYDROCHEM  HOLDING,  INC.,  a  Delaware
corporation  hereinafter  referred to as "Holding",  with offices at 900 Georgia
Avenue,  Deer Park,  Texas  77536,  all of the rights,  titles and  interests of
Industrial Services in, to and under:

                  1. That certain  Secured  Promissory Note dated April 9, 1998,
executed by B. Tom Carter, Jr. (the "Maker"), payable to the order of Industrial
Services in the original  principal amount of Two Hundred  Eighty-five  Thousand
Six Hundred One and No/100  Dollars  ($285,601.00),  bearing  interest and being
payable as therein provided (the "Note"); and

                  2. Any liens, security interests,  mortgages,  deeds of trust,
collateral agreements, security agreements, collateral assignments,  guaranties,
financing statements,  and other lien instruments executed by Maker, in favor of
Industrial Services, or any other party, in connection with the Note, including,
without limitation,  that certain Pledge Agreement dated April 9, 1998, executed
by Maker in favor of Industrial Services (the "Pledge Agreement").

                  Additionally,   Industrial  Services  agrees  to  execute  and
deliver such financing statement changes, assignments, amendments or supplements
as Holding may reasonably  request in order to comply with applicable law and to
preserve and protect Holding's rights, liens and security interests hereunder.

                  Industrial  Services also warrants and  represents  that it is
not aware of any event,  condition  or  circumstance  which,  with the giving of
notice or the passage of time or both, would constitute a default under the Note
or the Pledge Agreement.











<PAGE>


                  IN  WITNESS   WHEREOF,   the  undersigned  has  executed  this
Assignment of Note to be effective as of the 31st day of December, 1998.

HYDROCHEM INDUSTRIAL                             HYDROCHEM HOLDING, INC.
   SERVICES, INC.

By:   /s/ Selby F. Little, III                   By:   /s/ Pelham Smith
      ------------------------                         --------------------
      Selby F. Little, III                             Pelham Smith
      Executive Vice President, Chief                  Vice President, Assistant
      Financial Officer, and Assistant Secretary       Secretary and Assistant
                                                       Treasurer

THE STATE OF TEXAS   
COUNTY OF HARRIS     

                  BEFORE ME, the undersigned  authority,  on this day personally
appeared Selby F. Little,  III., the Executive Vice  President,  Chief Financial
Officer,  and  Assistant  Secretary of HydroChem  Industrial  Services,  Inc., a
Delaware  corporation,  known to me to be the person whose name is subscribed to
the foregoing  instrument and  acknowledged  to me that he executed the same for
the purposes and consideration therein expressed, in the capacity stated, and as
the act and deed of the banking association.

                  GIVEN  UNDER  HAND  AND  SEAL OF  OFFICE  this the 31st day of
December, 1998.

                                                      /s/ Lawanda Weidman
                                                      -------------------
                                                      Notary Public in and for
                                                      The State of Texas
THE STATE OF TEXAS   
COUNTY OF HARRIS      

                  BEFORE ME, the undersigned  authority,  on this day personally
appeared Pelham H. A. Smith, Vice President,  Assistant  Secretary and Assistant
Treasurer of HydroChem Holding, Inc., a Delaware corporation,  known to me to be
the person whose name is subscribed to the foregoing instrument and acknowledged
to me that he  executed  the same for the  purposes  and  consideration  therein
expressed,  in the  capacity  stated,  and as the  act and  deed of the  banking
association.

                  GIVEN  UNDER  HAND  AND  SEAL OF  OFFICE  this the 31st day of
December 1998.

                                                      /s/ Lawanda Weidman
                                                      -------------------
                                                      Notary Public in and for
                                                      The State of Texas


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