Agreement and Plan of Merger

Execution Version

[Form of Hamm Funding and Rollover Commitment Letter — HPGP Merger]

June 1, 2009

HH GP Holding, LLC
302 North Independence
Enid, Oklahoma 73701

Ladies and Gentlemen:

          Reference is made to the Agreement and Plan of Merger, dated the date hereof (the “ Merger Agreement ”), among you (“ Parent ”), HPGP MergerCo, LLC, a Delaware limited liability company and a subsidiary of Parent (“ Merger Sub ”), Hiland Partners GP Holdings, LLC, a Delaware limited liability company and the general partner of Holdings (“ Holdings GP ”), and Hiland Holdings GP, LP, a Delaware limited partnership (“ Holdings ” and, together with Holdings GP, the “ Holdings Parties ”). “ Trusts ” as used herein means the Harold Hamm DST Trust, for which Bert Harold Mackie is the trustee, and the Harold Hamm HJ Trust, for which Bert Harold Mackie is the trustee. Terms used and not defined herein have the meanings ascribed to such terms in the Merger Agreement.

          Prior to the Effective Time, and subject to (i) the terms and conditions of this letter agreement and (ii) the satisfaction or waiver (where permissible) of all of the conditions set forth in Sections 6.1 and 6.3 of the Merger Agreement, the undersigned hereby:

          (1) agrees to contribute to Parent $21,167,000.00 in cash, less the amount of cash, if any, immediately available to Parent or Merger Sub on the Closing Date that was contributed to Parent or Merger Sub by the Trusts (such amount, as so reduced, the “ Funding Commitment Amount ”); and

          (2) acknowledges that, in accordance with Section 2.1(b) of the Merger Agreement, each of the 59,600 Common Units owned by the undersigned will be unchanged and remain outstanding as Common Units of the Surviving Entity, and no consideration will be delivered in respect thereof.

           The undersigned agrees that the Holdings Parties shall be third party beneficiaries of this letter agreement in respect of the undersigned’s obligations, representations and warranties hereunder and, in such capacity and to the fullest extent permitted by law, are permitted to specifically enforce this letter agreement, provided that, to the fullest extent permitted by law, under no circumstances (including, without limitation, willful breach) shall the undersigned’s aggregate liability hereunder (i) exceed the Funding Commitment Amount or (ii) include any special, indirect, incidental, consequential or punitive damages or lost profits. Parent, by its acceptance of the benefits hereof, agrees and acknowledges that no person other than the undersigned shall have any obligation hereunder.

          The undersigned represents and warrants to Parent that (i) the undersigned has all requisite power and authority to execute, deliver, and perform this letter agreement and (ii) this letter agreement has been duly executed and delivered by the undersigned and constitutes a legal, valid and binding obligation of the undersigned, enforceable against the undersigned in accordance with its terms (except insofar as such enforceability may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and similar laws relating to or affecting creditors’ rights generally and by general principles of equity (regardless of whether such enforceability is considered in a proceeding in equity or at law)). The undersigned further represents and warrants to Parent that the undersigned has, and will have throughout the term of this letter agreement, sufficient cash or other immediately available funds to enable the undersigned to contribute the full Funding Commitment Amount.

          Neither this letter agreement nor any of the rights, interests or obligations hereunder shall be assigned by either party hereto (whether by operation of law or otherwise) without the prior written consent of the other party. This letter agreement may not be amended, supplemented or otherwise modified unless made by written instrument signed by both parties hereto, and Parent hereby agrees not to enter into any such amendment, supplement or modification, or to waive or fail to enforce any of its rights or interests hereunder, without the prior written consent of the Conflicts Committee of Holdings GP.

          Any term or provision of this letter agreement which is invalid or unenforceable in any jurisdiction shall, as to that jurisdiction, be ineffective only to the extent of such invalidity or unenforceability without rendering invalid or unenforceable such term o