Exhibit 10.10    February 20,
2008  Richard P. Eno 14 Cranston Road Winchester, MA 01890  Re: 
Employment Agreement  Dear Richard:  This letter is to confirm our understanding with
respect to your employment by Metabolix, Inc.
(the Company).  The terms and
conditions agreed to in this letter are hereinafter referred to as the Agreement.  In consideration of the mutual promises and
covenants contained in this Agreement, and for other good and valuable
consideration, the receipt and sufficiency of which are hereby mutually
acknowledged, we have agreed as follows:  1.Employment.  (a)General.  The Company
will employ you, and you will be employed by the Company, as President and
Chief Executive Officer of the Company, reporting to the Companys Board of
Directors (the Board),and you
shall have the responsibilities, duty and authority commensurate with that
position.  You will also perform such
other and/or different services for the Company as may be assigned to you from
time to time.  You agree that if your
employment hereunder ends for any reason, you will tender your resignation to
the Company of all offices with the Company as of the date of your termination.  (b)Devotion to Duties. 
While you are employed hereunder, you will use your best efforts, skills
and abilities to perform faithfully all duties assigned to you pursuant to this
Agreement and will devote your full business time and energies to the business
and affairs of the Company.  While you are
employed hereunder, you will not undertake any other employment from any person
or entity without the prior written consent of the Company.  You may, however, without prior approval of
the Company, serve as a member of the board of one other company or organization,
with or without compensation, provided that such membership does not conflict
with your obligations to the Company. You must seek advance approval from the
Company in the event you wish to serve as a member of a board of additional
companies or organizations.  2.Term.  The Company
hereby agrees to employ you, and you hereby accept employment with the Company,
upon the terms set forth in this Agreement, for the period commencing as of March 17,
2008 (the Commencement Date) and ending on the third


anniversary of the Commencement Date (such period is
the Agreement Term).  In the event the
Company wishes to renew this Agreement, the Company will provide written notice
to you of such desire at least 30 days before the expiration of the Agreement
Term.  3.Compensation.  (a)Base Salary. 
While you are employed hereunder, the Company will pay you a base salary
at the annual rate of no less than $25,000 per month (annualized at
$300,000.00) (the Base Salary).  The
Company will deduct from each monthly salary payment all amounts required to be
deducted or withheld under applicable law or under any employee benefit plan in
which you participate.  (b)Bonus Opportunity. 
You will be eligible to receive a cash bonus in an amount of up to 150%
of the Base Salary, based upon the Boards good faith assessment of your
achievement of individual goals, and of the Companys achievement of its
goals.  Individual and Company goals will
be established, and modified, in good faith by you and the Board. The Board
expects that the target bonus opportunity will be in the range of 70% of your
Base Salary if your performance fully meets those goals.To the extent the Board
awards you a cash bonus, the bonus, if payable, shall be calculated and paid no
later than two and a half months following the later of the close of the
calendar or of the Company fiscal year to which such bonus relates.  For your first year of employment, and any
other partial year of employment, your cash bonus will be awarded on a pro rata
basis.  (c)Equity Compensation.  (i)At the first
regularly scheduled meeting of the Boards Compensation Committee, but no later
than April 4, 2008, the Company shall grant you a stock option under the Metabolix, Inc.
2006 Stock Option and Incentive Plan, as amended February 22, 2007, and
restated (the 2006 Stock Plan), to purchase 100,000 shares of common stock of
the Company (the Initial Option) at an exercise price equal to the Fair
Market Value (as defined in the 2006 Stock Plan) of the Companys common stock
on the date of such grant.  Provided you
are employed by the Company on the vesting date, the Initial Option shall vest
as to 6,250 of the shares three months after the grant date and on the last day
of each three (3) month period following the first vesting date in equal
installments of 6,250 until the Initial Option fully vests. Except as provided
herein, the Initial Option will be subject to the terms and conditions of the
2006 Stock Plan and the customary terms and conditions of the Companys
standard form of stock option agreement.  (ii)Provided you remain employed with the
Company, on the six- month anniversary of the Commencement Date, the Company
shall grant you an Option under the Companys 2006 Stock Plan to purchase
50,000 shares of common stock of the Company (the Six Month Option) at an
exercise price equal to the Fair Market Value  2


of the Companys common stock on the date of such
grant.  Provided you are employed by the
Company on the vesting date, the Six Month Option shall vest as to 3,125 of the
shares three (3) months following the grant date and on the last day of
each three (3) month period following the first vesting date in equal
installments of 3,125 until the Six Month Option fully vests. Except as provided
herein, the Six Month Option will be subject to the terms and conditions of the
2006 Stock Plan and the customary terms and conditions of the Companys
standard form of stock option agreement.  (iii)Provided you are employed with the
Company on or after the first anniversary of the Commencement Date, and
provided the Compensation Committee determines that you have met the
performance goals established for you for the calendar year 2008, the Company
shall grant you an Option under the Companys 2006 Stock Plan to purchase
50,000 shares of common stock of the Company (the Bonus Option) at an
exercise price equal to the Fair Market Value of the Companys common stock on
the date of such grant.  Provided you are
employed by the Company on the vesting date, the Bonus Option shall vest as to
3,125 of the shares three (3) months following the grant date and on the
last day of each three (3) month period following the first vesting date
in equal installments of 3,125 until the Bonus Option fully vests. Except as
provided herein, the Bonus Option will be subject to the terms and conditions
of the 2006 Stock Plan and the customary terms and conditions of the Companys
standard form of stock option agreement.  (iv)To the extent allowed pursuant to Section 422
of the Internal Revenue Code of 1986, as amended (the Code), each option
referred to in subparagraphs (i) through (iii) hereof shall be deemed
to be an incentive stock option.  (d)Vacation.  You will be entitled to paid vacation and
paid holidays, accrued and used in accordance with the Companys policies as
currently in effect. All vacation days will be taken at times mutually agreed
by you and the Company and will be subject to the business needs of the
Company.  (e)Fringe Benefits.  You will be entitled to participate in
employee benefit plans which the Company provides or may establish for the
benefit of its senior executives generally (for example, group life,
disability, medical, dental and other insurance, retirement, pension,
profit-sharing and similar plans) (collectively, the Fringe Benefits).  Your eligibility to participate in the Fringe
Benefits and receive benefits thereunder will be subject to the plan documents
governing such Fringe Benefits.  Nothing
contained herein will require the Company to establish or maintain any Fringe
Benefits.  (f)Legal Fees.  The Company
shall reimburse your reasonable legal fees in connection with this Agreement,
upon the presentation of documentation supporting same, in an amount up to
$5,000.  3


(g)Reimbursement of Certain Expenses. 
You shall be reimbursed for such reasonable and necessary business
expenses incurred by you while you are employed by the Company, which are
directly related to the furtherance of the Companys business.  You
must submit any request for reimbursement no later than ninety (90) days
following the date that such business expense is incurred in accordance with
the Companys reimbursement policy regarding same and business expenses must be
substantiated by appropriate receipts and documentation.  If a business
expense reimbursement is not exempt from Section 409A of the Code, any
reimbursement in one calendar year shall not affect the amount that
may be reimbursed in any other calendar year and a reimbursement (or
right thereto) may not be exchanged or liquidated for another benefit or
payment.  Any business expense reimbursements subject to Section 409A
of the Code shall be made no later than the end of the calendar year following the
calendar year in which you incur such business expense.  4.Termination of the Term. 
The Term shall terminate upon the occurrence of any of the following:  (a)Termination of the Agreement Term. 
The Agreement shall terminate, upon no less than thirty days prior
written notice, at the expiration of the Agreement Term as set forth in Section 2.  (b)Termination for Cause. 
The Agreement shall terminate, at the election of the Company, for Cause
upon written notice by the Company to you. 
For the purposes of this Section, Cause for termination shall be
limited to the following:  (i)Your conviction of a felony; or  (ii)Your commission of fraud, or misconduct
that results in material and demonstrable damage to the business or reputation
of the Company; or  (iii)Your willful and continued failure to
perform your duties hereunder (other than such failure resulting from your
incapacity due to Disability, as defined herein) within 10 business days after
the Company delivers a written demand for performance to you that specifically
identifies the actions to be performed.  (c)Termination by the Company without Cause
or by You for Good Reason.  This Agreement shall terminate
at the election of the Company without Cause at any time upon 30 days prior
written notice by the Company to you, or by you for Good Reason (as defined
herein).  (d)Death or Disability. 
The Agreement shall terminate upon your death or disability. If you
shall be disabled so as to be unable to perform the essential functions of your
position under this Agreement with or without reasonable  4


accommodation, the Board may remove you from any
responsibilities and/or reassign you to another position with the Company
during the period of such disability, and such reassignment shall not trigger a
Good Reason termination as provided herein. 
Notwithstanding any such removal or reassignment, you shall continue to
receive your Base Salary (less any disability pay or sick pay benefits to which
you may be entitled under the Companys policies) and benefits under this
Agreement (except to the extent that you may be ineligible for one or more such
benefits under applicable plan terms) for a period of three months, and your
employment may be terminated by the Company at any time thereafter.  Nothing in this Section 4(b) shall
be construed to waive your rights, if any, under existing law including,
without limitation, the Family and Medical Leave Act of 1993, 29 U.S.C. §2601 et seq. and the Americans with
Disabilities Act, 42 U.S.C. §12101 et seq.  Notwithstanding the foregoing, if and only to the
extent that your disability is a trigger for the payment of deferred
compensation, as defined in Section 409A of the Code, disability shall
have the meaning set forth in Section 409A(a)(2)(C) of the Code.  (e)Termination by You. 
You may terminate this Agreement at your election upon not less than 30
days prior written notice to the Company.  (f)Definition of Good Reason. As used in this Agreement, Good
Reason means if the Company, without your written consent, fails to cure
any one or more of the event or circumstance listed below within 10 business
days after receiving notice from you:  (i)the assignment to you of duties
materially inconsistent with this Agreement or a material diminution in title
or authority;  (ii)any failure by the Company to pay you the
compensation and benefits to which you are entitled in any material way; or  (iii)the requirement that you relocate to a
location more than 50 miles outside of Cambridge, Massachusetts.  5.Effect of
Termination.  (a)In the event (i) you
are terminated for Cause; (ii) you are terminated for death or Disability;
or (iii) you voluntarily resign (other than for Good Reason), unless otherwise
specifically provided herein, you, or your estate, shall be eligible only to
receive (i) the portion of your Base Salary as has accrued prior to the
effectiveness of such termination and has not yet been paid, (ii) an
amount equal to the value of your accrued unused vacation days, and (iii) reimbursement
for expenses properly incurred by you on behalf of the Company prior to such
termination if such expenses are properly documented  5


in accordance with Company
policy and practice and submitted for reimbursement within 30 days of the
termination date (collectively, the Accrued Obligations).  Such amounts will be paid promptly after
termination in accordance with applicable law.  (b)In the event (i) you
are terminated without Cause; or (ii) you resign for Good Reason, in
addition to the Accrued Obligations, and contingent on your executing a
complete release of claims against the Company, and you do not revoke the
release (a fully effective release is hereafter, the Release), you shall be
entitled, in addition to the Accrued Obligations, to receive continuation of
your Base Salary in effect at the time of termination for the period of twelve
(12) months following your delivery of the Release.To the extent required by Section 409A of the
Code, the first installment of such Base
Salary in the amount of six (6) months Base Salary shall be payableon
the first business day following the six (6) month anniversary of the
effective date of termination, and the remainder shall be payable in accordance
with the Companys regular payroll procedures thereafter.  If Section 409A of the Code is not
applicable at the time of such termination, such Base Salary continuation shall
commence immediately after the date of the Release. In addition to the
foregoing, you shall be entitled to receive payment
of COBRA premiums to maintain medical and dental benefits, if any, in effect at
the time of termination for the earlier of (x) 12 months following the
termination and (y) the date you become insured under a medical insurance
plan providing similar benefits to that of the Company plan.  (c)In the event the
Agreement Term expires and you are terminated without Cause or you resign for
Good Reason (as defined in paragraph 4(f) above, and determined as if this
Agreement were still in effect) at or within six months of the expiration of
the Agreement Term, in addition to the Accrued Obligations, you shall be
entitled to the same benefits provided in Section 5(b) herein, upon your
execution of the Release, except that your Base Salary and COBRA premiums shall
be paid for a period of six (6) months following the date of your
termination.  The benefits in this
subsection are subject to the same limitations of 409A of the Code as set forth
in Section 5(b).  If your employment
continues after the expiration of this Agreement, this Section 5 (c),
Sections 4(b) and (f), and Sections 5(d) through (g) all shall
survive the termination of this Agreement for a period of six (6) months,
and Sections 3 (c), (d), (e) and (g) and Section 9(e)(ii) shall
survive the expiration of this Agreement for so long as you remain an employee
of the Company.  (d)Additional Benefits
Upon Termination in Connection With a Change of Control.In the event that your employment is
terminated by the Company without Cause or by you for Good Reason (each, as
defined herein) within 12 months immediately following or 6 months immediately
prior to a Change of Control, then, in addition to the Accrued Obligations and
the benefits described in Section 5(b), you shall be entitled to receive
full vesting of all unvested equity granted to you under the 2006 Stock Plan or
any authorized successor stock plan provided thatthe conditions to vesting other than the passage of time
have been satisfied. To the extent the Company grants you any other equity or
deferred compensation benefits, including, for example, restricted stock units,
phantom stock or  6


participation in a deferred compensation program, such
additional benefits shall similarly accelerate and vest upon a Change in
Control as provided herein.  (e)  The payments, benefits and
vesting, if any, to which you are entitled under Section 5 (and all other
payments, benefits and vesting to which you may be entitled) shall be provided
without regard to whether the deductibility of such payments, benefits and
vesting would be limited or precluded by Section 280G of the Code (Section 280G)
and without regard to whether such payments (or any other payment, benefits and
vesting) would subject you to the federal excise tax levied on certain excess
parachute payments under Section 4999 of the Code (the Excise Tax). 
If any portion of the payments, benefits and vesting to or for your benefit
(including, but not limited to, payments, benefits and vesting under this
Agreement but determined without regard to this paragraph) constitutes an excess
parachute payment within the meaning of Section 280G (the aggregate of
such payments being hereinafter referred to as the Excess Parachute Payments),
the Company shall promptly pay to you an additional amount (the gross-up
payment) that after reduction for all taxes (including but not limited to the
Excise Tax) with respect to such gross-up payment equals the Excise Tax with
respect to the Excess Parachute Payments; provided,
that to the extent any gross-up payment would be considered deferred
compensation for purposes of Section 409A of the Code, the manner and
time of payment, and the provisions of this Section 5(e), shall be
adjusted to the extent necessary (but only to the extent necessary) to comply
with the requirements of Section 409A with respect to such payment so that
the payment does not give rise to the interest or additional tax amounts
described at Section 409A(a)(1)(B) or Section 409A(b)(4) of
the Code (the Section 409A penalties); and
further provided, that if, notwithstanding the immediately preceding
proviso, the gross-up payment cannot be made to conform to the requirements of Section 409A
of the Code, the amount of the gross-up payment shall be determined without
regard to any gross-up for the Section 409A penalties.  The
determination as to whether your payments, benefits and vesting include Excess
Parachute Payments and, if so, the amount of such, the amount of any Excise Tax
owed with respect thereto, and the amount of any gross-up payment shall be made
at the Companys expense by such certified public accounting firm as the Board
may designate prior to a Change of Control (the accounting firm). 
Notwithstanding the foregoing, if the Internal Revenue Service shall assert an
Excise Tax liability that is higher than the Excise Tax (if any) determined by
the accounting firm, the Company shall promptly augment the gross-up payment to
address such higher Excise Tax liability. Notwithstanding anything in this
section to the contrary, the maximum amount of the gross-up payment, including
any gross-up for Section 409A penalties, shall not exceed $500,000.  (f)Change of Control.As used herein,
a Change of Control shall occur or be deemed to have occurred only upon any
one or more of the following events:  7


(i)any person (as such term is used in
Sections 13(d) and 14(d)(2) of the Securities Exchange Act of 1934,
as amended (the Exchange Act)) becomes a beneficial owner (as such term is
defined in Rule 13d-3 promulgated under the Exchange Act) (other than the
Company, any trustee or other fiduciary holding securities under an employee
benefit plan of the Company, or any corporation owned, directly or indirectly,
by the stockholders of the Company, in substantially the same proportions as
their ownership of stock of the Company), directly or indirectly, of securities
of the Company, representing fifty percent (50%) or more of the combined voting
power of the Companys then outstanding securities; or  (ii)persons who, as of the Effective Date,
constituted the Companys Board of Directors (the Incumbent Board) cease for
any reason including, without limitation, as a result of a tender offer, proxy
contest, merger, consolidation or similar transaction, to constitute at least a
majority of the Board of Directors, provided that any person becoming a
director of the Company subsequent to the Effective Date whose election was
approved by at least a majority of the directors then comprising the Incumbent
Board shall, for purposes of this Section 6(f), be considered a member of
the Incumbent Board; or  (iii)the consummation of a merger or
consolidation of the Company with any other corporation or other entity, other
than (1) a merger or consolidation which would result in the voting
securities of the Company outstanding immediately prior thereto continuing to
represent (either by remaining outstanding or by being converted into voting
securities of the surviving entity) more than fifty percent (50%) of the
combined voting power of the voting securities of the Company or such surviving
entity outstanding immediately after such merger or consolidation or (2) a
merger or consolidation effected to implement a recapitalization of the Company
(or similar transaction) in which no person (as hereinabove defined) acquires
more than fifty percent (50%) of the combined voting power of the Companys
then outstanding securities; or  (iv)the stockholders of the Company approve a
plan of complete liquidation of  the
Company or an agreement for the sale or disposition by the Company of all or
substantially all of the Companys assets.  (g)Separation from
Service.  Notwithstanding anything set
forth in Sections 4 and 5 of this Agreement, a termination of employment shall
be deemed not to have occurred until such time as you incur a separation from
service with the Company in accordance with Section 409a(a)(2)(A)(v) of
the Code and the applicable provisions of Treasury Regulation Section 1.409A-3.  8


6.Noncompetition, Confidentiality and
Inventions Obligations.  You agree to simultaneously
execute the Companys Employee Noncompetition, Confidentiality and Inventions
Agreement with the execution of this Agreement.  7.Disclosure to Future Employers. 
You will provide, and the Company, in its discretion, may similarly
provide, a copy of the covenants contained in the Employee Noncompetition,
Confidentiality and Inventions Agreement to any business or enterprise which
you may, directly or indirectly, own, manage, operate, finance, join, control
or in which you may participate in the ownership, management, operation,
financing, or control, or with which you may be connected as an officer,
director, employee, partner, principal, agent, representative, consultant or
otherwise.  8.Representations. 
You hereby represent and warrant to the Company that you understand this
Agreement, that you enter into this Agreement voluntarily and that your
employment under this Agreement will not conflict with any legal duty owed by
you to any other party.  9.General.  (a)Notices.  All notices, requests, consents and other
communications hereunder which are required to be provided, or which the sender
elects to provide, in writing, will be addressed to the receiving partys
address set forth above or to such other address as a party may designate by
notice hereunder, and will be either (i) delivered by hand, (ii) sent
by overnight courier, or (iii) sent by registered or certified mail,
return receipt requested, postage prepaid. 
All notices, requests, consents and other communications hereunder will
be deemed to have been given either (i) if by hand, at the time of the
delivery thereof to the receiving party at the address of such party set forth
above, (ii) if sent by overnight courier, on the next business day
following the day such notice is delivered to the courier service, or (iii) if
sent by registered or certified mail, on the 5th business day
following the day such mailing is made.  (b)Entire Agreement.  This Agreement, together with any Stock
Option Agreements executed by you and the Company (either prior to or in
conjunction with this Agreement) and the Employee Noncompetition,
Confidentiality and Inventions Agreement embody the entire agreement and
understanding between the parties hereto with respect to the subject matter
hereof and supersedes all prior oral or written agreements and understandings
relating to the subject matter hereof. 
No statement, representation, warranty, covenant or agreement of any
kind not expressly set forth in this Agreement will affect, or be used to
interpret, change or restrict, the express terms and provisions of this
Agreement.  (c)Modifications and
Amendments.  The terms and
provisions of this Agreement may be modified or amended only by written
agreement executed by the parties hereto.  9


(d)Waivers and
Consents.  The terms and
provisions of this Agreement may be waived, or consent for the departure
therefrom granted, only by written document executed by the party entitled to
the benefits of such terms or provisions.  No such waiver or consent will be deemed to be
or will constitute a waiver or consent with respect to any other terms or
provisions of this Agreement, whether or not similar.  Each such waiver or consent will be effective
only in the specific instance and for the purpose for which it was given, and
will not constitute a continuing waiver or consent.  (e)Assignment.  (i) The Company may assign its rights
and obligations hereunder to any person or entity that succeeds to all or
substantially all of the Companys business or that aspect of the Companys
business in which you are principally involved or to any Company
Affiliate.  (ii) You may not assign
your rights and obligations under this Agreement without the prior written
consent of the Company and any such attempted assignment by you without the
prior written consent of the Company will be void; provided, however, in the
event of your death, your rights, compensation and benefits under this
Agreement shall inure to the benefit of your estate, such that, for example,
stock issuable to you, and awards and payments payable to you, shall be issued
and paid to your estate.  (f)Governing Law.  This Agreement and the rights and obligations
of the parties hereunder will be construed in accordance with and governed by
the law of Massachusetts, without giving effect to the conflict of law
principles thereof.  (g)Jurisdiction, Venue
and Service of Process.  Any
legal action or proceeding with respect to this Agreement will be brought in
the courts of Massachusetts or of the United States of America for theDistrict of Massachusetts.  By execution and delivery of this Agreement,
each of the parties hereto accepts for itself and in respect of its property,
generally and unconditionally, the exclusive jurisdiction of the aforesaid
courts.  (h)Jury Waiver. You and the
Company agree to waive trial by jury in connection with any action arising from
or relating to this Agreement.  (h)Severability.  The parties intend this Agreement to be
enforced as written.  However, if any
portion or provision of this Agreement is to any extent declared illegal or
unenforceable by a duly authorized court having jurisdiction, then the
remainder of this Agreement, or the application of such portion or provision in
circumstances other than those as to which it is so declared illegal or
unenforceable, will not be affected thereby, and each portion and provision of
this Agreement will be valid and enforceable to the fullest extent permitted by
law.  (i)Headings and
Captions.  The headings
and captions of the various subdivisions of this Agreement are for convenience
of reference only and will in no way modify or affect the meaning or
construction of any of the terms or provisions hereof.  10


(j)Acknowledgments.  You recognize and agree that the enforcement
of the Noncompetition, Nondisclosure and Inventions Agreement may be necessary
to ensure the preservation, protection and continuity of the business, trade
secrets and goodwill of the Company.  You
agree that, due to the proprietary nature of the Companys business, the
restrictions set forth in the Noncompetition, Confidentiality and Inventions
Agreement may be reasonable as to time and scope.  (k)Taxes.All payments required to be made by the Company to you
under this Agreement shall be subject to the withholding of such amounts for
taxes and other payroll deductions as the Company may reasonably determine it
should withhold pursuant to any applicable law or regulation.  To the extent
applicable, it is intended that this Agreement comply with the provisions of Section 409A
of the Code, and this Agreement shall be construed and applied in a manner
consistent with this intent.  In the
event that any severance payments or benefits hereunder are determined by the
Company to be in the nature of nonqualified deferred compensation payments, you
and the Company hereby agree to take such actions as may be mutually agreed to
ensure that such payments or benefits comply with the applicable provisions of Section 409A
of the Code and the official guidance issued thereunder.  Notwithstanding the foregoing, the
Company does not guarantee the tax treatment or tax consequences associated
with any payment or benefit arising under this Agreement.  (l)Counterparts.  This Agreement may be executed in two or more
counterparts, and by different parties hereto on separate counterparts, each of
which will be deemed an original, but all of which together will constitute one
and the same instrument.  If
the foregoing accurately sets forth our agreement, please so indicate by
signing and returning to us the enclosed copy of this Agreement.  Very truly yours,  Metabolix, Inc.  By:
  
  /s/ Anthony
  J. SinskeyName:
  
  Anthony J. SinskeyTitle:
  
  Chairman of the Compensation Committee  Accepted and Approved:  /s/ Richard
  P. Eno
  
  2/20/08Richard P. Eno
  
  Date   11