EXHIBIT 10.13

         AMENDMENT NO. 2 TO SENIOR SUBORDINATED NOTE PURCHASE AGREEMENT

         AMENDMENT NO 2. as of dated June 30, 1998 to Senior  Subordinated  Note
Purchase Agreement dated as of October 31, 1997, as amended, between NuCo2 Inc.,
the Subsidiary  Guarantors and the Investors (the "Agreement").  All capitalized
terms used herein and not  otherwise  defined  shall have the meanings  accorded
them in the Agreement.

         WHEREAS, the Company, the Subsidiary  Guarantors and the Investors have
entered into the Agreement; and

         WHEREAS,  the Company,  the  Subsidiary  Guarantors  and the  Investors
desire to amend the Agreement.

         NOW, THEREFORE,  for good and valuable  consideration,  the receipt and
sufficiency  of which are  hereby  acknowledged,  the  Company,  the  Subsidiary
Guarantors and the Investors agree as follows:

         1.       Section 8.09(a) of the Agreement is amended in its entirety to
read as follows:

                  "(a) INTEREST  COVERAGE RATIO. The Company will not permit the
Interest  Coverage Ratio to be less than the following  respective  ratios as at
the last day of each fiscal quarter during the following respective periods:

                           PERIOD                            RATIO
                           ------                            -----

                  From the Closing Date
                    through June 30, 1998                 1.25 to 1.00

                  From July 1, 1998
                     through December 31, 1998            1.40 to 1.00

                  From January 1, 1999
                     through March 31, 1999               1.50 to 1.00

                  From April 1, 1999
                     through June 30, 1999                1.65 to 1.00

                  From July 1, 1999
                     through September 30, 1999           1.80 to 1.00

                  From October 1, 1999
                     through December 31, 1999            2.00 to 1.00

                  From January 1, 2000
                     through March 31, 2000               2.25 to 1.00

                  From April 1, 2000
                     and at all times thereafter          2.50 to 1.00"

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         2. Section  8.09(b) of the Agreement is amended in its entirety to read
as follows:

                  "(b) TOTAL NET FUNDED DEBT  COVERAGE  RATIO.  The Company will
not permit  the Total Net Funded  Debt  Coverage  Ratio to exceed the  following
respective ratios at any time during the following respective periods:

                           PERIOD                              RATIO
                           ------                              -----

                  From the Closing Date
                    through September 30, 1998             7.00 to 1.00

                  From October 1, 1998
                     through December 31, 1998             6.50 to 1.00

                  From January 1, 1999
                     through March 31, 1999                5.50 to 1.00

                  From April 1, 1999
                     through June 30, 1999                 5.00 to 1.00

                  From July 1, 1999
                     and at all times thereafter           4.50 to 1.00"

         3. The Company  represents and warrants to the Investors that (a) as of
the date hereof and after giving effect to the amendments provided in Sections 1
and 2 hereof, (i) the  representations and warranties set forth in Article VI of
the  Agreement  are true and complete on the date hereof as if made on and as of
the date hereof and as if each reference in said Article VI to "this  Agreement"
(or words of similar import) referred to the Senior  Subordinated  Note Purchase
Agreement  as  amended  by this  Amendment  No.  2 except  that (w) the  lawsuit
described  in Schedule  6.06(a) has been settled by the Company and is no longer
pending,  (x) certain of the indebtedness  listed in Schedule 6.12 has been paid
off by the Company,  (y) the number of validly issued and outstanding  shares of
common  stock,  par value  $0.001  per  share,  referenced  in  Section  6.13 is
7,216,664 and (z) the number of outstanding  options granted under the Company's
stock  option  plans  has  changed  and  (ii) no  Default  has  occurred  and is
continuing  and (b) the amendment to certain of the Warrants as set forth in the
letter  dated as of the date  hereof  from the Company to certain of the Holders
(as defined in the Warrant Agreement) have been duly authorized by all necessary
corporate  action  on the part of the  Company  and such  letter  has been  duly
executed  and  delivered  by the Company  and such  letter and such  Warrants as
amended thereby constitute valid and legally binding obligations of the Company,
enforceable  against it in accordance  with their  respective  terms,  except as
enforcement  may be limited by bankruptcy,  insolvency or similar laws affecting
creditors' rights generally,  and by general principles of equity (regardless of
whether enforcement is sought at equity or in law).

         4. Except as herein provided,  the Agreement shall remain unchanged and
in full force and effect.  This Amendment No. 2 may be executed in any number of
counterparts,  all of which taken  together  shall  constitute  one and the same
amendatory  instrument  and any of the parties hereto may execute this Amendment
No. 2 by signing any such  counterpart.  This  Amendment No. 2 shall be governed
by, and construed in accordance with, the law of the State of New York.

         IN WITNESS WHEREOF, the parties hereto have caused this Amendment No. 2
to be duly executed and delivered as of the day and year first above written.



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                              COMPANY:

                              NUCO2 INC.

                              By: /S/ JOANN SABATINO
                                  ----------------------
                                  Name: Joann Sabatino
                                  Title: CFO

                              SUBSIDIARY GUARANTORS:

                              NUCO2 ACQUISITION CORP.

                              By: /S/ JOANN SABATINO
                                  ----------------------
                                  Name: Joann Sabatino
                                  Title: Treasurer

                              KOCH COMPRESSED GASES, INC.

                              By: /S/ JOANN SABATINO
                                  ----------------------
                                  Name: Joann Sabatino
                                  Title: Treasurer

                              INVESTORS:

                              CHASE EQUITY ASSOCIATES L.P.

                              By: Chase Capital Partners, its general partner

                              By: /S/ JOHN M.B. O'CONNOR
                                  --------------------------
                                  Name: John M.B. O'Connor
                                  Title: General Partner

                              DK ACQUISITION PARTNERS, L.P.

                              By: M.H. Davidson & Co., its general partner

                              By: /S/ THOMAS L. KEMPNER, JR.
                                  ------------------------------
                                  Name: Thomas L. Kempner, Jr.
                                  Title: Partner

                              EMPIRE  INSURANCE  COMPANY, as executed on their
                              behalf by their Investment Manager, Cohanzick
                              Management, L.L.C.

                              By: ______________________________
                                  Name:
                                  Title:

                              ORIX USA CORPORATION

                              By: /S/ HIROYUKI MIYAUCHI
                                  -------------------------
                                  Name: Hiroyuki Miyauchi
                                  Title: Executive Vice President

                              PAINEWEBBER HIGH INCOME FUND, a series of
                              PaineWebber Managed Investments Trust

                              By: ______________________________
                                  Name: