PIONEER NATURAL RESOURCES COMPANY SEVERANCE AGREEMENT

PIONEER NATURAL RESOURCES COMPANY

SEVERANCE AGREEMENT

This Severance Agreement ( “Agreement” ) is entered into, as of May 19, 2008, among Pioneer Natural Resources Company, a Delaware corporation ( “Parent” ), Pioneer Natural Resources USA, Inc., a Delaware corporation that is a wholly-owned subsidiary of Parent ( “Employer” ) and Frank Hall ( “Employee” ). As used henceforth in this Agreement, the term “Company” shall be deemed to include Parent and its direct or indirect majority-owned subsidiaries.

Recitals

Parent and Employer acknowledge that Employee possesses skills and knowledge instrumental to the successful conduct of the Company’s business. Parent and Employer are willing to enter into this Agreement with Employee in order to better ensure themselves of access to the continued services of Employee.

NOW, THEREFORE, for and in consideration of the mutual covenants and agreements set forth herein and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties to this Agreement hereby agree as follows:

1.     Term . The term of this Agreement shall commence on the date indicated above (the “Effective Date” ) and end on September 30, 2008. Thereafter, on the date on which the term of this Agreement (as it may be extended from time to time under this paragraph 1) would otherwise expire, so long as Employee is still an employee of the Company on such date, such term will be automatically extended for 12 months, unless Parent shall have provided written notice to Employee at least 6 months before the date that the term would otherwise expire that it does not want the term to be extended. Parent may deliver a conditional notice of non-renewal that will be effective only if Employee does not agree, within the time period specified by Parent, to any amendment or modification of this Agreement that Parent shall request be executed as a condition to allowing the term hereof to be extended. Notwithstanding the foregoing, so long as Employee is in the employ of the Company on the date on which a Potential Change in Control occurs, the term of this Agreement shall continue in effect following such Potential Change in Control until the date on which the term of any separate agreement between Parent and Employer and Employee relating to the provision of severance and other benefits after a Change in Control (the “ Change in Control Agreement ”) expires; provided, however, that upon the occurrence of such a Change in Control, this Agreement shall terminate and such Change in Control Agreement shall govern the rights of Employee to, or obligations of Parent and Employer to provide, severance and other benefits to Employee.

2.     Certain Definitions . As used in this Agreement, the following terms shall have the meanings set forth below:

(a)    “Accrued Obligations” shall mean any vested amounts or benefits owing to Employee under any of the Company’s employee benefit plans and programs in which Employee has participated, including any compensation previously deferred by Employee (together with any accrued earnings thereon) and not yet paid.

(b)     Across-the-Board Salary Reduction” shall mean a reduction in Employee’s Base Salary that is a part of, and is at a level consistent with, a reduction in the base salaries paid to substantially all employees of Company who are parties to an agreement with the Company that would provide them with severance and other termination benefits in the event of an involuntary termination of employment by the Company who without cause prior to the occurrence of a Change in Control.

(c)     “Base Salary” shall mean Employee’s annualized base salary at the rate in effect at the relevant date or event as reflected in Employer’s regular payroll records.

(d)    “Change in Control” shall mean an event that constitutes a “change in control” as defined in Parent’s Long-Term Incentive Plan (the “LTIP” ), as in effect on the Effective Date or as subsequently amended from time to time (except that any amendment to such definition adopted (1) on or within 180 days prior to a Change in Control or Potential Change in Control or (2) on or after a Potential Change in Control shall not be applied in determining the definition of such term under this Agreement unless such amendment is favorable to Employee).

(1)      In the case of a termination for which a Notice of Termination is required, the date of receipt of such Notice of Termination or, if later, the date specified therein; and

(2)      In all other cases, the actual date on which Employee’s employment terminates.

(f)      “Disability” shall mean Employee’s physical or mental impairment or incapacity of sufficient severity such that

(1)      In the opinion of a qualified physician selected by Parent, after taking into account all reasonable accommodations that the Company has made or could make, Employee is unable to continue to perform Employee’s duties and responsibilities as an employee of the Company; or

(2)      Employee’s condition entitles Employee to long-term disability benefits under any employee benefit plan maintained by the Company in which Employee participates.

For purposes of subparagraph (f)(1), Employee agrees to provide such access to Employee’s medical records and to submit to such physical examinations or medical tests as, in the opinion of the physician selected by Parent, is reasonably necessary to make the determination required as to Employee’s ability to perform Employee’s duties and responsibilities. If such physician is unable to render an opinion as to Employee’s ability to perform such duties and responsibilities due to Employee’s failure to provide such access to any of Employee’s medical records or to submit to any such examination or test (unless, in the opinion of such physician such failure is a direct result of Employee’s physical or mental impairment), any failure by Employee to perform Employee’s duties and responsibilities shall be deemed not to be on account of Employee’s physical or mental impairment or incapacity.

(g)    “Earned Salary” shall mean the Base Salary earned by Employee, but unpaid, through Employee’s Date of Termination.

(1)      A reduction in Employee’s Base Salary that is not an Across-the-Board Salary Reduction and that, when combined with the net effect of all prior reductions in Employee’s Base Salary (other than prior reductions that were Across-the-Board Salary Reductions), results in the Base Salary then payable to Employee being less than 80% of the highest Base Salary which Employee has ever received from the Company (as reflected in Employer’s regular payroll records); or

(2)      A reduction in Employee’s Base Salary (whether or not an Across-the-Board Salary Reduction) that, when combined with the net effect of all prior reductions in Employee’s Base Salary (whether or not Across-the-Board Salary Reductions), results in the Base Salary payable to Employee being less than 65% of the highest Base Salary which Employee has ever received from the Company (as reflected in Employer’s regular payroll records).

(i)      “Normal Retirement Date” shall mean the date on which Employee attains age 60.

(j)      “Notice of Termination” shall mean a written notice given by the party effecting the termination of Employee’s employment which shall

(1)      Indicate the specific termination provision in this Agreement relied upon;

(2)      Set forth in reasonable detail the facts and circumstances claimed to provide a basis for termination of Employee’s employment under the provision so indicated; and

(3)      If the Date of Termination is other than the date of receipt of such notice, specify the Date of Termination (which date shall be not more than 30 days after the giving of such notice).

The failure by Employee or Parent or Employer to set forth in the Notice of Termination any fact or circumstance which contributes to a showing of Termination for Good Reason or Termination for Cause shall not waive any right of such party hereunder or preclude such party from asserting such fact or circumstance in enforcing such party’s rights hereunder. In the event that a Potential Change in Control has occurred, any Notice of Termination by Parent or Employer intended to effect a Termination for Cause must be given with 45 days of Parent or Employer’s having actual knowledge of the events giving rise to Termination for Cause.

(k)     “Potential Change in Control” shall mean the occurrence of any of the following events:

(1)      Any person or group shall have announced publicly an intention to effect a Change in Control, or commenced any action (such as the commencement of a tender offer for Parent's common stock or the solicitation of proxies for the election of any of Parent’s directors) that, if successful, could reasonably be expected to result in the occurrence of a Change in Control;

(2)      Parent enters into an agreement the consummation of which would constitute a Change in Control; or

(3)      Any other event occurs which the Board of Directors of Parent (the “Board” ) declares to be a Potential Change in Control.

(l)      “Separation Payment” shall mean any lump sum payment in excess of Earned Salary and Accrued Obligations payable to Employee under this Agreement.

(m)    “Termination for Cause” shall mean a termination of Employee’s employment by the Company following the occurrence of any of the following:

(1)      Employee’s continued failure to substantially perform Employee’s duties and responsibilities (other than any such failure resulting from Employee’s physical or mental impairment or incapacity);

(2)      Employee’s engaging in fraud or other misconduct that is injurious to the Company, monetarily or otherwise;

(4)      Employee’s violation of, or failure to comply with, any material written policy, guideline, rule or regulation of the Company;

(5)      Employee’s conviction of (or plea of guilty or nolo contendere to a charge of) any felony, or any crime or misdemeanor involving moral turpitude or financial misconduct;

(6)      Employee’s failure, following a written request from Parent, reasonably to cooperate (including, without limitation, the refusal by Employee to be interviewed or deposed, or to give testimony) in connection with any investigation or proceeding, whether internal or external (including, without limitation, by any governmental or quasi-governmental agency) into the business practices or operations of the Company; or

(7)      A material violation by Employee of the provisions of paragraphs 5 or 6 of this Agreement.

(n)    “Termination for Good Reason” shall mean a termination of Employee’s employment by Employee within 30 days after

(1)      the earlier of receipt by Employee of (i) written notice of an Excessive Salary Reduction and (ii) Employee’s first paycheck that reflects an Excessive Salary Reduction; or

(2)      if Employee is an officer of Parent or Employer, the demotion of Employee to either a non-officer position or an officer position with such entity

that is junior to the officer position held by Employee immediately prior to such demotion.

(a)    Right to Terminate . Nothing in this Agreement shall be construed in any way to limit the right of the Company to terminate Employee’s employment, with or without cause, or for Employee to terminate Employee’s employment with the Company, with or without reason; provided, however, that the Company and Employee must nonetheless comply with any duty or obligation such party has at law or under any agreement (including paragraphs 5 and 6 of this Agreement) between the parties.

(b)    Termination due to Death or Disability . Employee’s employment with the Company shall be terminated upon Employee’s death. By written notice to the other party, either the Company or Employee may terminate Employee’s employment due to Disability.

(c)     Relocation . Nothing in this Agreement shall be construed in any way to limit the right of the Company to require Employee to perform Employee’s services on behalf of the Company at a different location or locations than the one at which Employee was performing Employee’s services immediately prior to the date hereof, or to require the Company to pay or provide any benefits to Employee on account of such relocation, other than to the extent benefits would be payable to Employee under the Company’s applicable relocation policy as in effect at the relevant time.

4.     Amounts Payable Upon Termination of Employment . The following provisions shall apply to any termination of Employee’s employment:

(a)    Death, Disability or Normal Retirement . In the event that Employee’s employment terminates due to Employee’s death or Disability (regardless of whether such Disability termination is initiated by Employee or the Company), or due to the voluntary retirement by Employee (which is not a Termination for Good Reason) at or after attaining Employee’s Normal Retirement Date, Parent or Employer shall pay Employee (or, if applicable, Employee’s beneficiaries or legal representative(s)):

(1)      The Earned Salary, as soon as practicable (but not more than 10 days) following Employee’s Date of Termination;

(2)      The Accrued Obligations, in accordance with applicable law and the provisions of any applicable plan, program, policy or practice; and

(3)      A Separation Payment in an amount equal to Employee’s Base Salary, which shall be paid, in all cases other than voluntary retirement on or after Normal Retirement Date, within 10 days following Employee’s Date of Termination, and, in the case of voluntary retirement on or after Normal Retirement Date, 6 months and 1 day after Employee’s Date of Termination.

(b)    Cause and Voluntary Termination . If Employee’s employment is terminated by the Company in a Termination for Cause or voluntarily by Employee (other than in a Termination for Good Reason or at or after Normal Retirement Date), Parent or Employer shall pay Employee

(1)      The Earned Salary, as soon as practicable (but not more than 10 days) following Employee’s Date of Termination; and

(2)      The Accrued Obligations, in accordance with applicable law and the provisions of any applicable plan, program, policy or practice.

(c)     Termination for Good Reason or Not for Cause . If Employee terminates Employee’s employment in a Termination for Good Reason, or the Company terminates Employee’s employment for any reason other than those described in paragraphs 4(a) and (b) above, Parent or Employer shall pay or shall provide to Employee the following benefits and compensation:

(1)   &