SUPPLEMENTAL EXECUTIVE RETIREMENT AGREEMENT

Exhibit 10.1

SUPPLEMENTAL EXECUTIVE RETIREMENT AGREEMENT

THIS SUPPLEMENTAL EXECUTIVE RETIREMENT AGREEMENT (the “Agreement”) made and entered into as of this 15th day of November, 2006 (the “Effective Date”), by and between BANCFIRST, an Oklahoma banking corporation (the “Company”), and Darryl Schmidt (the “Executive”).

Now, therefore, in consideration of services to be performed in the future as well as of the mutual promises and covenants herein contained, the parties agree as follows:

ARTICLE I

Definitions

1.1 Definitions. Whenever used in this Agreement, the following words and phrases shall have the meanings specified:

(a) Cause means termination of the Executive’s employment by the Company for one of the following reasons: (i) insubordination; (ii) disloyalty; (iii) breach of this Agreement; (iv) theft, dishonesty or other unlawful conduct; or (v) other similar cause, including failure to perform duties in accordance with the instructions of the Company.

(b) Change of Control means the direct or indirect occurrence of any of the following:

(i) Company sells substantially all of its assets to a single purchaser or to a group of associated purchasers;

(ii) at least two-thirds (2/3) of the outstanding shares of common stock of the Company are sold, exchanged, or otherwise disposed of, in one transaction; or

(iii) there is a merger or consolidation of the Company in a transaction in which the holders of the Company’s common stock receive or represent less than fifty percent (50%) of the outstanding voting shares of the new or continuing corporation.

(c) Death Benefit means the benefit payable to Executive’s Surviving Spouse or other designated beneficiary pursuant to Section 2.3 hereof.

(d) Supplemental Retirement Income means the benefit payable to the Executive pursuant to Article II hereof.

(e) Surviving Spouse shall mean only the then surviving spouse of the Executive as of the date of the Executive’s death.

ARTICLE II

Supplemental Retirement Income

2.1 Supplemental Retirement Income. Subject to the terms of this Agreement, if an Executive remains continually employed with the Company until age 65, the Executive shall be entitled to a Supplemental Retirement Income of $100,000 per year for a period of ten (10) years commencing on the first day of the month coinciding with or next following the date the Executive attains age 65; provided, these Supplemental Retirement Income payments shall commence as of such date whether or not the Executive continues to be employed by the Company beyond age 65. Executive’s Supplemental Retirement Income shall be payable on a monthly basis. If the Executive dies during the ten year period of Supplemental Retirement Income payments, the Executive’s Surviving Spouse or other designated beneficiary shall receive the remaining payments over the remainder of the ten year period.

2.2 Payment of Benefit upon Termination Without Cause. Upon the occurrence of a Change of Control or after Executive reaches age 59, if Executive is terminated without Cause prior to reaching age 65, Executive shall be entitled to receive a single lump sum distribution of the present values (based on a discount rate of 6%) of Executive’s Supplemental Retirement Income. This lump sum distribution will be paid within 90 days of Executive’s termination of employment and shall be in lieu of the Supplemental Retirement Income, or any other payment due Executive under this Agreement.

2.3 Death Benefit. If the Executive dies while still employed with the Company, but before age 65, the Company shall pay a Death Benefit to the Surviving Spouse or if the Executive has previously elected otherwise, to a designated beneficiary, in the form of a lump sum distribution. The amount of the Death Benefit shall be calculated as a fraction of the total lump sum amount of the Executive’s Supplemental Retirement Income. The Fraction shall be calculated with the numerator being the total number of months between the Effective Date of this Agreement and the Executive’s death and the denominator being the total months between the Effective Date of this Agreement and the date the Executive would have reached age 65; provided further, this lump sum payment shall be paid within sixty (60) days of Executive’s date of death. The Death Benefit payable under this Section shall be in lieu of the Supplemental Retirement Income, or any other payment otherwise due Executive under this Agreement.

2.4 Termination of Employment Prior to Age 59 or For Cause. Except as otherwise provided in this Article II, if Executive ceases to be employed by the Company (i) for any reason (other than death) prior to reaching age 59 or (ii) prior to reaching age 65 the Executive is terminated by the Company for Cause, the Executive shall not be entitled to any benefit under this Agreement.

ARTICLE III

General Limitations

3.1 No Trust. No action under this Agreement by the Company shall be construed as creating a trust, escrow or other secured or segregated fund in favor of Executive. The status of the Executive with respect to any liabilities assumed by the Company hereunder shall be solely those of unsecured creditors of the Company. Any asset acquired or held by the Company in connection with liabilities assumed by it hereunder shall not be deemed to be held under any trust, escrow or other secured or segregated fund for the benefit of the Executive or to be security for the

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performance of the obligations of the Company, but shall be, and remain, a general, unpledged, unrestricted asset of the Company, at all times subject to the claims of general creditors of the Company. It is also intended that for federal income tax purposes and for purposes of Title I of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), that this Agreement shall at all times be unfunded.

3.2 No Assignability. Neither the Executive nor any other person shall acquire any right to or interest in any Supplemental Retirement Income, or any other benefit under this Agreement otherwise than by actual payment in accordance with the provisions of this Agreement, or have any power to transfer, assign, anticipate, pledge, mortgage or otherwise encumber, alienate or transfer any rights hereunder in advance of any of the payments to be made pursuant to the Agreement or any portion thereof, which is expressly declared to be nonassignable and nontransferable. No right or benefit hereunder shall in any manner be subject to the debts, contracts, liabilities, or torts of the Executive. If the Executive should become bankrupt or attempt to anticipate, alienate, sell, assign, pledge, encumber, or charge any right to a benefit under this Agreement, then such right or benefit shall, in the discretion of the Company, cease and terminate, and, in such event, the Company may hold or apply the same or any part thereof for the benefit of the Executive, in such manner and in such portion as the Company, in its sole and absolute discretion, may deem proper.

3.3 Agreement Does Not Guarantee Continued Employment of the Executive. The execution of this Agreement by the Company and the Executive in no way whatsoever guarantees the continuation of employment of the Executive with the Company.

3.4 Withholding. Since the payment of Supplemental Retirement Income is compensation, the Company and the Executive shall comply with all federal and state laws and regulations respecting the withholding, deposit and payment of any income, employment or other taxes relating to any payments made under this Agreement.

3.5 Limitation on Payment of Benefits. Payments under this Agreement shall accrue and be payable only at such times and upon the occurrence of such conditions as heretofore described. In no event whatsoever shall the Executive have any right, claim, or interest of any kind whatsoever in any future payments of such benefits and such payments shall a