MANAGEMENT DEFERRED COMPENSATION PLAN

EXHIBIT 10.20

MANAGEMENT DEFERRED COMPENSATION PLAN

Effective — January 1, 2008

As Last Amended Effective July 16, 2008

E. I. du Pont de Nemours and Company

Article 1. Purpose

E. I. du Pont de Nemours and Company (“Company”) desires to provide certain of its employees with an opportunity to accumulate additional retirement savings through voluntary compensation deferral contributions to a plan intended to constitute a non-qualified deferred compensation plan which, in accordance with Sections 201(2), 301(a)(3) and 401(a)(1) of the Employee Retirement Income Security Act of 1974, as amended (“ERISA”), is unfunded and maintained by the Company primarily for the purpose of providing deferred compensation for a select group of management or highly compensated employees. The Company intends that a participant’s compensation deferrals, and the earnings thereon, will not be subject to federal income tax until such amounts are paid or made available to the participant.

Article 2. Definitions

Section 2.01 “ Account ” means each account established on the books of account of the Employer to reflect the balance of Plan benefits attributable to a Participant. An Account shall be credited or debited, as applicable, with Deferral Contributions, Credited Investment Return and Dividend Equivalent Units, and any payments made by the Employer to the Participant or the Participant’s Beneficiary pursuant to this Plan. A Participant’s Account shall be divided into Directed Investment Subaccounts, with respect to which he/she shall be permitted to make Deemed Investment Elections, and Stock Unit Subaccounts, with respect to which he/she shall not be permitted to make Deemed Investment Elections.

Section 2.02 “ Active Participant ” means a Participant on whose behalf a current Deferral Election is in effect.

Section 2.03 “ Administrator ” means the Company.

Section 2.04 “ Affiliate ” means any corporation, organization or entity which is under common control with the Company or which is otherwise required to be aggregated with the Company pursuant to paragraphs (b), (c), (m), or (o) of Section 414 of the Code.

Section 2.05 “ Base Salary ” means the basic pay from the Employer (excluding LTI Awards and STI Awards, distributions from nonqualified deferred compensation plans, commissions, overtime, severance, fringe benefits, stock options and other equity awards, relocation expenses, incentive payments, non-monetary awards, automobile and other allowances (whether or not such allowances are included in the Employee’s gross income) and other non-regular forms of compensation paid to a Participant for employment services rendered). Base Salary shall be calculated before reduction for compensation voluntarily deferred or contributed by the Participant pursuant to all qualified or nonqualified plans of any

Employer and shall be calculated to include amounts not otherwise included in the Participant’s gross income under Code Sections 125, 132, 402(e)(3), 402(h), or 403(b) pursuant to plans or arrangements established by any Employer; provided, however, that all such amounts will be included in Base Salary only to the extent that had there been no such plan, the amount would have been payable in cash to the Employee. Notwithstanding anything in this Plan to the contrary, Base Salary shall not include any amount paid pursuant to a disability plan or pursuant to a disability insurance policy.

Section 2.06 “ Base Salary Deferral Eligible Employee ” means any U.S.-based employee of the Employer who is designated from time to time by the Employer as eligible to defer the payment of Base Salary in accordance with Article 4 hereof.

Section 2.07 “ Beneficiary ” means the person or persons designated as such pursuant to Article 7 hereof.

Section 2.08 “ Change of Control ” means an objectively determined event that occurs with respect to the Company or the Employer for whom the Participant renders services and which constitutes both a Change in Control for purposes of the Equity and Incentive Plan and change in the ownership or effective control of the Company or Employer, as applicable, or in the ownership of a substantial portion of the Company’s or Employer’s, as applicable, assets for purposes of Code Section 409A.

Section 2.09 “ Code ” means the Internal Revenue Code of 1986, as amended, and the regulations and rulings issued thereunder.

Section 2.10 “ Common Stock Unit ” means a notional unit representing one share of common stock of the Company.

Section 2.11 “ Credited Investment Return ” means the hypothetical gain or loss credited to a Participant’s Directed Investment Subaccounts pursuant to Article 5 hereof.

Section 2.12 “ Deemed Investment Election ” means the selection by a Participant, pursuant to Article 5 hereof, of Investment Options in which his/her Directed Investment Subaccounts shall be deemed invested.

Section 2.13 “ Deferral Contributions ” means the elective contributions made to the Plan by a Participant pursuant to Article 4 hereof.

Section 2.14 “ Deferral Election ” means an election, pursuant to Article 4 hereof, to defer receipt of Base Salary or STI Awards, or the settlement of LTI Awards.

Section 2.15 “ Directed Investment Subaccount ” means that portion of a Participant’s Account to which a Participant’s Deferral Contributions of Base Salary and STI Awards, and Credited Investment Return and Dividend Equivalent Units attributable thereto, will be allocated and with respect to which he/she may make Deemed Investment Elections in accordance with Article 5 hereof. A Participant may maintain no more than five (5) Directed Investment Subaccounts under this Plan.

Section 2.16 “ Dividend Equivalent Units ” means additional Common Stock Units credited to a Participant’s Account pursuant to Section 5.05.

Section 2.17 “ Dividend Payment Date ” means each date on which the Company pays a dividend on its common stock.

Section 2.18 “ Effective Date ” means January 1, 2008. Notwithstanding the foregoing to the contrary, provisions of this Plan related to the deferral of Base Salary and LTI Awards shall not be effective until January 1, 2009.

Section 2.19 “ Eligible Employee ” means any Base Salary Deferral Eligible Employee, STI Deferral Eligible Employee or LTI Deferral Eligible Employee.

Section 2.20 “ Employer ” means the Company and any Affiliate which, with the consent of the Company, adopts this Plan.

Section 2.21 “ Equity and Incentive Plan ” means the E.I. du Pont de Nemours and Company Equity and Incentive Plan.

Section 2.22 “ Form of Payment ” means either (i) a lump sum or (ii) annual installments (for up to fifteen (15) years). Annual installments are available only in connection with a Separation from Service or Change of Control. In the event of a Participant’s death, his/her remaining Account balance will be distributable in a single lump sum.

Section 2.23 “ Identification Date ” means each December 31.

Section 2.24 “ Investment Options ” means one or more alternatives designated from time to time, pursuant to Section 5.01 hereof, for purposes of crediting earnings or losses to Directed Investment Subaccounts.

Section 2.25 “ LTI Award ” means an award of RSUs or PSUs.

Section 2.26 “ LTI Deferral Eligible Employee ” means any U.S.-based employee of the Employer who is designated from time to time by the Company as eligible to defer the settlement of an LTI Award in accordance with Article 4 hereof.

Section 2.27 “ Participant ” means any Eligible Employee who has elected to participate in the Plan by completing the appropriate forms (including electronic forms) prescribed by the Administrator for that purpose.

Section 2.28 “ Payment Event ” means any of the following:

     (a) Separation from Service

     (b) The earlier of (i) Separation from Service or (ii) a specified date

     (c) Change of Control

     Notwithstanding the foregoing, (i) in the event of a Participant’s death, his/her remaining Account balance will automatically be distributed to his/her Beneficiary in a single lump sum within ninety days (90) thereafter and (ii) a Participant may request that all or a portion of his/her Account be distributed on account of an “unforeseeable emergency” as defined in Treasury Regulation Section 1.409A-3(i)(3) and subject to the restrictions on such distributions set forth therein.

Section 2.29 “ Plan ” means the E.I du Pont de Nemours and Company Management Deferred Compensation Plan.

Section 2.30 “ Plan Year ” means the twelve (12) month period beginning January 1 and ending December 31.

Section 2.31 “ PSU ” means a performance-based restricted stock unit granted under the Equity and Incentive Plan.

Section 2.32 “ Qualified Leave ” means military leave, sick leave, or other bona fide leave of absence if the period of such leave does not exceed six months, or if longer, so long as the individual retains a right to reemployment with the service recipient under an applicable statute or by contract. A leave of absence constitutes a bona fide leave of absence only if there is a reasonable expectation that the employee will return to perform services for the employer. If the period of leave exceeds six months and the individual does not retain a right to reemployment under an applicable statute or by contract, the employment relationship is deemed to terminate on the first date immediately following such six-month period.

Section 2.33 “ RSU ” means a time-vested restricted stock unit granted under the Equity and Incentive Plan.

Section 2.34 “ Section 16 Person ” means any employee who is subject to the reporting requirements of Section 16(a) or the liability provisions of Section 16(b) of the Securities and Exchange Act of 1934, as amended.

Section 2.35 “ Separation from Service ” means a “separation from service” as defined in Treasury Regulation Section 1.409A-1(h).

Section 2.36 “ Similar Plan ” means a plan required to be aggregated with this Plan under Treasury Regulation Section 1.409A-1(c)(2)(i)(A).

Section 2.37 “ Specified Employee ” means an officer of the Employer at any time during the 12-month period ending on an Identification Date. If a Participant is a Specified Employee as of an Identification Date, such Participant is treated as a Specified Employee for the 12-month period beginning on the first day of the first month following the Identification Date.

Section 2.38 “ STI Award ” means a cash-based award under the Equity and Incentive Plan.

Section 2.39 “ STI Deferral Eligible Employee ” means any U.S.-based employee of the Employer who is designated from time to time by the Employer as eligible to defer the payment of an STI Award in accordance with Article 4 hereof.

Section 2.40 “ Stock Unit Subaccount ” means that portion of a Participant’s Account to which a Participant’s Deferral Contributions of LTI Awards, and Dividend Equivalent Units attributable thereto, will be allocated and with respect to which he/she may not make Deemed Investment Elections in accordance with Article 5 hereof. A Participant may maintain no more than five (5) Stock Unit Subaccounts under this Plan.

Section 2.41 “ Triggering Event ” means, with respect to a Distribution Subaccount, the Payment Event elected by a Participant pursuant to Section 4.03.

Article 3. Eligibility.

Section 3.01 Procedure For and Effect of Admission. Each Eligible Employee who desires to participate in this Plan shall complete such forms (including electronic forms) and provide such data as is reasonably required by the

Administrator. By becoming a Participant, an Eligible Employee shall be deemed to have consented to the provisions of this Plan and all amendments hereto.

Section 3.02 Cessation of Participation. A Participant shall cease to be an Active Participant on the earlier of:

     (a) The date on which the Plan terminates;

     (b) The date on which he/she ceases to be an Eligible Employee; or

     (c) The date on which he/she is permitted by the Administrator to terminate Deferral Contributions to the Plan.

     A former Active Participant will be considered a Participant for all purposes, except with respect to the right to make contributions, as long as he/she retains an Account.

Article 4. Deferral Elections

Section 4.01 Annual Deferral Election.

(a) Deferral Contributions of Base Salary. Prior to the last day of the calendar year preceding the first day of a Plan Year, a Base Salary Deferral Eligible Employee may elect, in a written or electronic notification to the Administrator, to defer a percentage, not to exceed 60%, of his/her Base Salary payable with respect to services performed during the Plan Year. Any election made pursuant to this section shall remain in effect unless and until changed by the Participant; provided, however, that with respect to Base Salary earned in any future taxable year, such election becomes irrevocable on December 31 of the preceding calendar year.

(b) Deferral Contributions of STI Awards. With respect to any STI Award, an STI Deferral Eligible Employee may elect, in a written or electronic notification to the Company on or before the sixth month prior to the last day of the performance period over which the STI Award shall be determined, to defer a percentage, not to exceed 60%, of such STI Award; provided, however, that such STI Deferral Eligible Employee performs services continuously from the later of the beginning of the performance period or the date the performance criteria are established through the date the election to defer is made. Such election shall remain in effect unless and until changed by the Participant; provided, however, that with respect to any STI Award earned during any future taxable year, such election becomes irrevocable no later than six (6) months before the end of the performance period over which the STI Award shall be determined.

(c) Deferral Contributions of LTI Awards.

(i) RSUs . On or before the last day of the calendar year preceding the first day of a Plan Year, an LTI Deferral Eligible Employee may elect to defer the settlement of RSUs granted during such Plan Year. Notwithstanding the foregoing, an LTI Deferral Eligible Employee may elect to defer the settlement of RSUs that are subject to a vesting period of at least 12 months, provided such election is made on or before the thirtieth (30th) day after the LTI Deferral Eligible Employee is granted the RSUs and further provided that the election is made at least 12 months in advance of the earliest date on which the vesting period could expire. In the event that a timely election to defer the settlement of RSUs may not be made pursuant to either of the foregoing sentences of this paragraph, an LTI Deferral Eligible Employee may elect to defer the settlement of RSUs provided such election is made at least 12 months in advance of the date on which the restrictions on such RSUs lapse and further provided that such RSUs may not be settled until the fifth anniversary of the date that the restrictions on the RSUs lapsed. Notwithstanding the foregoing to the contrary, an LTI Deferral Eligible Employee shall not be permitted to elect to defer the settlement of RSUs unless such election complies with Code Section 409A. If a Participant elects to defer settlement of RSUs, any restrictions on transferability and/or events of forfeiture applicable to such RSUs under the Equity and Incentive Plan or the Award Terms (as defined

under the Equity and Incentive Plan) shall continue in full force and effect. Upon expiration of all restrictions on transferability, the appropriate number of Common Stock Units of the Company, including Dividend Equivalent Units attributable thereto, shall be credited to the Participant’s applicable Stock Unit Subaccount. Any election made pursuant to this Section shall remain in effect unless and until changed by the Participant; provided, however, that with respect to RSUs granted in any future taxable year, such election becomes irrevocable on or before the last day of the calendar year preceding the Plan Year during which the RSUs are granted or, if later, on or before the thirtieth (30th) day after the LTI Deferral Eligible Employee is granted the RSUs and at least 12 months in advance of the earliest date on which the vesting period could expire.

(ii) PSUs . An LTI Deferral Eligible Employee may elect, in a written or electronic notification to the Company on or before the sixth month prior to the last day of the performance period over which the PSUs shall be determined, to defer the settlement of such PSUs. Such election shall remain in effect unless and until changed by the Participant; provided, however, that with respect to any PSUs earned during any future taxable year, such election becomes i