Exhibit 10.16


                                 AMENDMENT NO. 5

            AMENDMENT  NO.  5 dated  as of May 12,  2000  to the  Note  Purchase
Agreement referred to below, between:

            NUCO2 INC., a corporation  duly organized and validly existing under
the laws of the State of Florida (the "Company");

            each of the Subsidiaries of the Company  appearing under the caption
      "SUBSIDIARY  GUARANTORS" on the signature pages hereto (each a "Subsidiary
      Guarantor" and, collectively,  the "Subsidiary Guarantors";  and, together
      with the Company, the "Obligors"); and

            each of the Investors appearing under the caption "INVESTORS" on the
      signature  pages  hereto  (each,  an  "Investor",  and  collectively,  the
      "Investors").

            WHEREAS,  the  Obligors  and the  Investors  are  party  to a Senior
Subordinated Note Purchase Agreement dated as of October 31, 1997 (as heretofore
modified and supplemented  and in effect on the date hereof,  the "Note Purchase
Agreement"),  pursuant to which the Company has issued to the  Investors its 12%
Senior  Subordinated  Notes in an  aggregate  principal  amount  of  $40,000,000
outstanding on the date hereof; and

            WHEREAS,  the parties to the Note Purchase  Agreement  wish to amend
the Note Purchase Agreement to make certain modifications thereto;

            Accordingly, the parties hereto hereby agree as follows:

            Section  1.  Definitions.   Except  as  otherwise  defined  in  this
Amendment No. 5, terms defined in the Note Purchase Agreement are used herein as
defined therein.

            Section 2.  Amendments  to Note Purchase  Agreement.  Subject to the
satisfaction  of the  conditions  precedent  specified  in Section 5 below,  but
effective as of the date hereof, the Note Purchase Agreement shall be amended as
follows:

            A.  References  in the Note Purchase  Agreement to "this  Agreement"
(and indirect references such as "hereunder",  "hereby",  "herein" and "hereof")
shall be deemed to be  references  to the Note  Purchase  Agreement  as  amended
hereby.

            B. Section 1.01 of the Note Purchase  Agreement  shall be amended by
adding the following new definitions (to the extent not already included in said
Section 1.01) and inserting the same in the appropriate  alphabetical  locations
and amending the following  definitions (to the extent already  included in said
Section 1.01):

<PAGE>

                                       -2-

            "Consolidated Net Worth" means, as of the date of determination, the
      sum of, without duplication, (a) total shareholders' equity of the Company
      and its  Subsidiaries  on a consolidated  basis,  determined in accordance
      with GAAP, and (b) the 8% Convertible Preferred Stock.

            "8% Convertible  Preferred  Stock" means the Company's 8% Cumulative
      Convertible  Preferred  Stock, no par value,  having an aggregate  initial
      liquidation preference of $5,000,000.

            C. The  definition  of  "Indebtedness"  in Section  1.01 of the Note
Purchase  Agreement  shall be amended by  inserting  a new  sentence  at the end
thereof to read as follows: "Notwithstanding the foregoing, "Indebtedness" shall
exclude the 8% Convertible Preferred Stock."

            D. Section 8.05 of the Note Purchase  Agreement  shall be amended in
its entirety to read as follows:

            "SECTION 8.05  Restricted  Payments.  The Company will not, and will
      not permit any of its Subsidiaries to, declare or make, or agree to pay or
      make,  directly or  indirectly,  any  Restricted  Payment,  except (a) the
      Company may declare and pay  dividends  with respect to its capital  stock
      payable solely in additional  shares of its common stock,  (b) the Company
      may make  Restricted  Payments  pursuant to and in  accordance  with stock
      option plans or other  benefit  plans for  management  or employees of the
      Company and its  Subsidiaries,  (c) the Company may  repurchase  or redeem
      shares of any class of capital stock of the Company issued pursuant to and
      in  accordance  with  stock  option  plans  or  other  benefit  plans  for
      management  or  employees  or under other  option plans of the Company not
      exceeding $1,000,000 in the aggregate, (d) the Company may declare and pay
      dividends  with respect to its capital  stock in an  aggregate  amount not
      exceeding the net proceeds of any equity issuance by the Company after the
      Closing Date (other than the 8%  Convertible  Preferred  Stock) (minus the
      aggregate  amount of any Investments made from such proceeds under Section
      8.04(a)(viii))  and (e) the Company may accrue and cumulate  (but not pay,
      except as  permitted  under  clause (d) above)  cash  dividends  on the 8%
      Convertible Preferred Stock."

            E. Section 8.09 of the Note Purchase  Agreement  shall be amended in
its entirety to read as follows:

            "SECTION 8.09 Financial Covenants.

            (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:
<PAGE>
                                      -3-
                      Period                             Ratio
                      ------                             -----

              From April 1, 1999
                through March 31, 2000                1.25 to 1.00

              From April 1, 2000
                through June 30, 2000                 1.15 to 1.00

              From July 1, 2000
                through September 30, 2000            1.25 to 1.00

              From October 1, 2000
                through December 31, 2000             1.35 to 1.00

              From January 1, 2001
                through March 31, 2001                1.50 to 1.00

              From April 1, 2001
                through June 30, 2001                 1.70 to 1.00

              From July 1, 2001
                through September 30, 2001            1.90 to 1.00

              From October 1, 2001
                through December 31, 2001             2.15 to 1.00

              From January 1, 2002
                through March 31, 2002                2.25 to 1.00

              From April 1, 2002
                and at all times thereafter           2.50 to 1.00

            (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 October 1, 1999
                through December 31, 1999             5.50 to 1.00

              From January 1, 2000
                through March 31, 2000                5.00 to 1.00

              From April 1, 2000
                through June 30, 2000                 6.00 to 1.00

              From July 1, 2000
                through September 30, 2000            5.60 to 1.00

<PAGE>

                                      -4-

              From October 1, 2000
                through December 31, 2000             5.25 to 1.00

              From January 1, 2001
                through March 31, 2001                5.00 to 1.00

              From April 1, 2001
                through June 30, 2001                 4.75 to 1.00

              From July 1, 2001
                and at all times thereafter           4.50 to 1.00

            (c)  Minimum  Net Worth.  The  Company  shall at all times  maintain
      Consolidated  Net Worth of not less than the sum of (a)  $37,500,000,  (b)
      plus 50% of the cumulative Consolidated Net Income for each fiscal quarter
      ending on or after December 31, 1997 (but  specifically  not including any
      Consolidated Net Loss for any such fiscal quarter) plus (c) the cumulative
      net  proceeds  of  all  equity  offerings  (if  any)  (other  than  the 8%
      Convertible  Preferred  Stock) made by the Company for each fiscal quarter
      ending on or after September 30, 1997."

            Section 3. Waiver.  Subject to the  satisfaction  of the  conditions
specified in Section 4 below, but with effect on and after the date hereof,  the
Investors  hereby agree to waive any Default that has occurred and is continuing
on the date  hereof as a result of the  Company's  failure to comply as of March
31,  2000 with the  requirements  under  Section  8.09(b)  of the Note  Purchase
Agreement (as in effect immediately prior to the effectiveness of this Amendment
No. 5).

            Section 4.  Representations  and Warranties.  The Company represents
and warrants to the Investors that: (a) the  representations  and warranties set
forth in Article VI of the Note Purchase  Agreement (as amended hereby) 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 Note Purchase Agreement as amended by this Amendment No.
5 (except that (i) certain of the  indebtedness  listed in Schedule  6.12 to the
Note  Purchase  Agreement  has been paid off by the Company,  (ii) the number of
validly  issued and  outstanding  shares of common  stock,  par value $0.001 per
share,  referred to in Section 6.13 of the Note Purchase  Agreement is 7,274,682
and (iii) the number of outstanding  options  granted under the Company's  stock
option  plans has  changed);  and (b) (after  giving  effect to the waiver under
Section 3 above) no Default has occurred and is continuing.

            Section 5.  Conditions  Precedent.  As  provided in Sections 2 and 3
above,  the amendments to the Note Purchase  Agreement set forth in said Section
2, and the waiver under the Note Purchase  Agreement set forth in said Section 3
shall become  effective,  as of the date hereof,  upon the  satisfaction  of the
following conditions:

<PAGE>

                                      -5-

            (a)  Amendment  No. 5. The  execution  and  delivery  of one or more
      counterparts  of this  Amendment  No. 5 by the  Obligors  and the Required
      Investors, and receipt by the Investors of evidence that the lenders party
      to the Senior Credit Agreement shall have approved this Amendment No. 5.

            (b) Third  Amendment  to Senior  Credit  Agreement.  Receipt  by the
      Investors of a copy of the Third Amendment to the Senior Credit Agreement,
      in substantially  the form heretofore  delivered to each of the Investors,
      as executed by the parties thereto.

            (c)  Other  Documents.  Receipt  by  the  Investors  of  such  other
      documents as any Investor may reasonably request.

            Section  6.  Miscellaneous.  Except  as  herein  provided,  the Note
Purchase  Agreement  shall remain  unchanged and in full force and effect.  This
Amendment  No. 5 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. 5 by signing any such
counterpart.  This  Amendment  No. 5 shall be  governed  by,  and  construed  in
accordance with, the law of the State of New York.



<PAGE>

            IN WITNESS  WHEREOF,  the parties  hereto have caused this Amendment
No. 5 to be duly  executed  and  delivered  as of the day and year  first  above
written.

                                   NUCO2 INC.


                                   By: /s/ Eric M. Wechsler
                                       ------------------------
                                    Title: General Counsel, Secretary


                                   SUBSIDIARY GUARANTORS

                                   NUCO2 ACQUISITION CORP.


                                   By: /s/ Eric M. Wechsler
                                       ------------------------
                                     Title: Vice President


                                   KOCH COMPRESSED GASES, INC.


                                   By: /s/ Eric M. Wechsler
                                       ------------------------
                                     Title: Vice President


<PAGE>

                                    INVESTORS


                                    CHASE CAPITAL INVESTMENTS, L.P.

                                    By Chase Capital Partners,
                                     its Investment Manager


                                    By: /s/ Richard D. Waters
                                     Title: General Partner - Mezzanine


                                    DK ACQUISITION PARTNERS, L.P.

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


                                    By: /s/ Thomas Kempner
                                        ----------------------
                                      Title: Partner


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


                                   By_________________________
                                     Title:


                                   ORIX USA CORPORATION


                                   By: /s/____________________
                                     Title: Executive Vice President



<PAGE>

                                      -8-


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


                                   By: /s/ Diane O'Donnell
                                       -----------------------
                                     Title: Vice President and Secretary


                                   SUNTRUST BANKS, INC.


                                   By: /s/ Robert Dudiak
                                       ---------------------
                                    Title: Group Vice President