Exhibit 10.26  THIRD
AMENDMENT TO LEASE  Definitions:  Effective Date:
  December 28, 2009Landlord:
  Harvard University, founded in 1636, being an
  educational and charitable corporation established under the Harvard Charter
  of 1650 from the General Court of the Massachusetts Bay Colony, whose
  corporate name is President and Fellows of Harvard College.Tenant:
  A123 Systems, Inc., a Delaware corporation.Lease:
  Lease between Landlord, as landlord, and Tenant, as
  tenant, dated as of June 1, 2004, as amended by that certain First
  Amendment to Lease dated as of February 9, 2007, as further amended by
  that certain Second Amendment to Lease dated as of March 28, 2009 (the Second
  Amendment).Existing Premises:
  All of Building 60 (as defined in the First
  Amendment) containing approximately 10,993 rentable square feet of space, all
  as more particularly described in the Lease (the Original Premises);
  and a portion of the third floor of Building 312 containing approximately
  9,894 rentable square feet of space, as more particularly described in the
  Lease (the First Amendment Expansion Premises).Third AmendmentExpansion Premises:
  A portion of the second floor of Building 313
  containing approximately 3,506 rentable square feet of space, as more particularly
  described on Exhibit A attached hereto.Third AmendmentExpansion PremisesCommencement Date:
  December 28, 2009Third AmendmentExpansion PremisesRent Commencement Date:
  February 1, 2010.  All capitalized terms not
otherwise defined herein shall have the meanings set forth in the Lease.  BACKGROUND:  Tenant desires to expand
the Premises and to extend the Lease Expiration Date, and Landlord has agreed
to such expansion and extension upon the terms and conditions set forth below,
and provided certain other revisions are made to the Lease, all as set forth
more particularly below.  Landlord and Tenant
hereby agree as follows:  1.Expansion Premises:  Landlord will
deliver the Third Amendment Expansion Premises to Tenant as of the Third
Amendment Expansion Premises Commencement Date, and Tenant agrees to accept the
Third


Amendment
Expansion Premises broom clean and free of all occupants but otherwise in its
AS-IS condition, and Landlord shall have no obligation to do any work or make
any installation or alterations of any kind to the Third Amendment Expansion
Premises.  Each of the Third Amendment
Expansion Premises Commencement Date and the Third Amendment Expansion Premises
Rent Commencement Date shall be extended on a day-for-day basis for each day
after December 28, 2009 that Landlords failure to deliver the Third
Amendment Expansion Premises in the above-required condition persists.  2.Amended Definitions:  (a)As of the Third Amendment Expansion Premises
Commencement Date the following terms wherever they appear in the Lease shall
have the following meanings:  Lease
Expiration Date:April 30,
2011, or such earlier or later date upon which the Lease Term with respect to
the applicable premises may expire, be terminated or extended pursuant to any
of the conditions or other provisions of this Lease or pursuant to law.  Basic
Rent:Original Premises Basic Rent, First
Amendment Expansion Premises Basic Rent and Third Amendment Expansion Premises
Rent.  Original Premises Basic Rent:  Period
  
  AnnualBasic Rent
  
  MonthlyBasic RentLease Year 1
  
  $
  271,527.10
  
  $
  22,627.26Lease Year 2
  
  $
  282,520.10
  
  $
  23,543.34Lease Year 3
  
  $
  293,513.10
  
  $
  24,459.43Lease Year 4
  
  $
  304,506.10
  
  $
  25,375.51Lease Year 5and through April 30, 2011
  
  $
  315,499.10
  
  $
  26,291.59  First Amendment Expansion
Premises Basic Rent:  Period
  
  AnnualBasic Rent
  
  MonthlyBasic RentLease Year 1
  (commencing on the Expansion Premises Rent Commencement Date)
  
  $
  277,032.00
  
  $
  23,086.00Lease Year 2
  
  $
  286,926.00
  
  $
  23,910.50Lease Year 3and through April 30, 2011
  
  $
  296,820.00
  
  $
  24,735.00  2


Third Amendment
Expansion Premises Basic Rent:  Period
  
  AnnualBasic Rent
  
  MonthlyBasic RentThird Amendment
  Expansion Premises Rent Commencement Date - April 30, 2011
  
  $
  105,180.00
  
  $
  8,765.00  Tenants
Share of Parking Spaces:63 unreserved parking spaces
located in the Complex to be used in accordance with Section 2.7.  3.Third Amendment Expansion Premises
Expense Allocation and Tax Reimbursement; Utilities. 
Tenant shall have no Expense Allocation or Tax Reimbursement obligations
with respect to the Third Amendment Expansion Premises.  Tenant shall pay all charges for its use of electricity
in the Third Amendment Expansion Premises. Electricity charges for the Third
Amendment Expansion Premises will be determined by Landlord based on check
meters installed in the Building, will be billed to Tenant in arrears on a
monthly basis and shall be due on the next Rent Payment Date after the date of
such invoice.  4.Lease Term Extension Option.  Section 10
of the Lease and Section 5 of the Second Amendment are hereby deleted in
their entirety and Tenant shall have no further rights to extend the Lease
Term.  5.Broker. 
Tenant warrants and represents to Landlord that it has not dealt with
any broker other than Beal and Company, Inc. (the Broker) and T3 Realty Advisors in
connection with this Amendment.  In the
event of any brokerage claims against Landlord (excluding claims made by the
Broker) predicated on prior dealings by the Tenant hereto with the maker of
such claims, Tenant shall defend, indemnify, and hold Landlord harmless against
all loss and expense incurred by Landlord (including reasonable attorneys fees).  Landlord shall be responsible for any
brokerage commission payable to the Broker pursuant to separate agreement.  6.Ratification. 
Except as expressly modified by this Amendment, the Lease shall remain
in full force and effect, and as further modified by this Amendment, is
expressly ratified and confirmed by the parties hereto.  7.Miscellaneous. 
This Amendment (i) contains the entire agreement with respect to
the subject matter hereof; (ii) may not be modified or terminated, nor may
any provision hereof be waived, orally or in any manner other than by an
agreement in writing signed by the parties hereto or their respective
successors, and assigns; (iii) shall be governed by and construed in
accordance with the laws of The Commonwealth of Massachusetts; (iv) may be
executed in multiple counterparts, each of which individually shall be deemed
an original and all of which together shall constitute a single original
agreement; and (v) shall inure to the benefit of, and be binding upon, the
parties hereto, and their successors, and assigns, subject to the provisions of
the Lease regarding assignment and subletting. Any termination of the Lease
shall also terminate and render void all rights of Tenant under this
Amendment.  Tenants rights under this
Amendment may not be severed from the Lease or separately sold, separately
assigned, or separately transferred.  [Remainder of Page Left Intentionally Blank]  3


IN WITNESS WHEREOF,
Landlord and Tenant have executed this Amendment under seal effective as of the
Effective Date.   PRESIDENT AND FELLOWSOF HARVARD COLLEGEBy:
  /s/ Robert W. IulianoName:
  Robert W. IulianoTitle:
  Vice President and General
  CounselBy:
  /s/ James W. GrayName:
  James W. GrayTitle:
  Assoc. V.P. of Harvard
  Real Estate ServicesA123 SYSTEMS, INC.By:
  /s/ Michael RubinoName:
  Michael RubinoTitle:
  CFO


EXHIBIT A  THIRD AMENDMENT EXPANSION PREMISES