Exhibit
      10.1


    July
      25,
      2007


    


    The
      Dow
      Chemical Company

    2030
      Dow
      Center

    Midland,
      MI 48674

    Attention:
      James H. Plonka


    


    
      	 	
              Re:

            	
              Amendment
                of Certain Terms of the Joint Development Arrangement between Millennium
                Cell Inc. and The Dow Chemical
                Company.

            


    

     

    Ladies
      and Gentlemen:

    


    Reference
      is made to the following agreements: (i) the Joint Development Agreement, dated
      as of April 25, 2005, as amended May 30, 2006, by Millennium Cell Inc. (the
      “Company”),
      and
      The Dow Chemical Company (“TDCC”)
      (the
“JDA”),
      (ii)
      the Registration Rights Agreement, dated as of April 25, 2005, by the Company
      and TDCC (the “RRA”),
      (iii)
      the Investor Rights Agreement, dated as of April 25, 2005, by the Company and
      TDCC (the “IRA”),
      (iv)
      the Stock Purchase Agreement, dated as of February 27, 2005, as amended April
      25, 2005 and May 30, 2006, by the Company and TDCC (the “SPA”),
      and
      (v) the Letter Agreement, by the Company and TDCC, dated as of January 26,
      2007
      (the “Letter
      Agreement”).
      Reference is also made to that certain Certificate of Designations of
      Preferences, Limitations, and Relative Rights of Series B Convertible Preferred
      Stock of the Company, as filed with the Office of the Secretary of State of
      the
      State of Delaware on April 25, 2005 and as amended by the Certificate of
      Amendment filed with the Office of the Secretary of State of the State of
      Delaware on June 30, 2005 (the “Series
      B Certificate”).
      Reference is also made to that certain Certificate of Designations of
      Preferences, Limitations, and Relative Rights of Series A2 Convertible Preferred
      Stock of the Company, as filed with the Office of the Secretary of State of
      the
      State of Delaware on June 30, 2005 (the “Series
      A2 Certificate”).

    


    The
      purpose of this letter is to (i) amend the JDA, the SPA, the RRA, and the Letter
      Agreement, (ii) terminate the IRA, (iii) effect a waiver of certain of TDCC’s
      rights under the Series A2 Certificate and the Series B Certificate, (iv) effect
      a waiver of certain of the Company’s rights under the SPA and the JDA and (v)
      confirm that Milestone 2 has been achieved.

     

    Achievement
      of Milestone 2

     

    
      	
            	1)	
              The
                Company and TDCC hereby agree that Milestone 2 (as defined in the
                JDA) was
                achieved on June 30, 2007 and that the parties have satisfied all
                of their
                obligations under Section
                9.5(a)
                of
                the JDA and Sections
                4.10(a)
                and (c)
                of
                the SPA necessary for Milestone 2 to be conclusively deemed to have
                been
                achieved as of such date. 

            


    

    
 

    
      
         

      

      
         

        
          

        

      

      
         

      

    

     

    Joint
      Development Agreement 

     

    
      	
            	2)	
              Pursuant
                to Section 13.7 of the JDA, TDCC and the Company hereby consent to
                amend
                the JDA, and the JDA is hereby amended, as
                follows:

            


    

     

    
      	 	
              a)

            	
              The
                seventh “WHEREAS”
                clause is hereby amended by (i) deleting “, 3 and 4” and substituting “and
                3” therefor and (ii) inserting “or Common Stock” after “Series A Preferred
                Stock”.

            


    

     

    
      	 	
              b)

            	
              The
                eighth “WHEREAS”
                clause is hereby amended by deleting “, 2, 3 and 4” and substituting “and
                2” therefor.

            


    

     

    
      	 	
              c)

            	
              The
                last two (2) sentences of Section
                2.1
                are hereby amended and restated in their entirety as follows:
                

            


    

     

    “By
      performing these obligations, MCEL will seek to cause the occurrence of the
      Military Objectives and the Consumer Objectives (if any) contained in the three
      (3) milestones described in this Article
      2
      (each, a
“Milestone”
and,
      collectively, the “Milestones”)
      and,
      as a result of the occurrence of all the Military Objectives or the Consumer
      Objectives in any such Milestone, will achieve such Milestone as set forth
      in
      the Milestone Table. Upon the achievement of Milestone 1 and Milestone 2, Dow
      will be entitled to receive Series A Preferred Stock and to purchase Series
      B
      Preferred Stock and receive Warrants, subject to the terms and conditions of
      this Agreement and the other Transaction Agreements. Upon the achievement of
      Milestone 3, Dow will be entitled to receive Common Stock, subject to the terms
      and conditions of this Agreement and the other Transaction Agreements;
provided,
      however,
      that
      the Company may, at its option, satisfy its obligations with respect to
      Milestone 3 by paying Dow in cash.”

     

    
      	 	
              d)

            	
              The
                descriptive caption and the first sentence of Section
                2.2
                are hereby amended and restated in their entirety as follows:
                

            


    

     

    “Milestones
      1, 2 and 3.
      Each of
      the three (3) Milestones (“Milestone
      1,”
      “Milestone
      2”
and
      “Milestone
      3,”
      respectively) shall be achieved upon any of: (i) the achievement of all of
      the
      Military Objectives corresponding to such Milestone in the Milestone Table
      set
      forth on Exhibit
      B
      of this
      Agreement (the “Milestone
      Table”),
      (ii)
      the achievement of all of the Consumer Objectives corresponding to such
      Milestone in the Milestone Table, or (iii) the occurrence of a Sale or
      Merger.”

     

    
      	 	
              e)

            	
              Clause
                (iii) in the second sentence of Section
                2.2
                is
                hereby deleted in its entirety.

            


    

     

    
      	 	
              f)

            	
              Section
                4.2(a)
                is
                hereby modified by deleting the words “Milestone 4” and substituting the
                words “Milestone 3” therefor.

            


    

     

     

    
      
         

      

      
        -2-

        
          

        

      

      
         

      

    

     

     

    
      	 	
              g)

            	
              Section
                4.2(d)
                and Section
                4.2(e)
                are hereby deleted in their
                entirety.

            


    

     

    
      	 	
              h)

            	
              Section
                4.2(f)
                is
                hereby modified by deleting the words “Milestone 4” and substituting the
                words “Milestone 3” therefor.

            


    

     

    
      	 	
              i)

            	
              Section
                4.2(i)
                is
                hereby amended and restated in its entirety as
                follows:

            


    

     

    “(i)
      MCEL
      Consumer Tasks -
      Milestone 3.
      From
      the date of achievement of Milestone 2 until the achievement of the Consumer
      Objectives contained in Milestone 3, MCEL shall (i) design, build and test
      a
      prototype solid state Hydrogen on Demand® generator (Solid State HODTM)
      appropriate for consumer electronics applications; and (ii) if applicable,
      identify and exercise reasonable best efforts to engage in discussions with
      potential licensees and consumer electronics device manufacturers.”

     

    
      	 	
              j)

            	
              Section
                4.2(j)
                is
                hereby deleted in its entirety.

            


    

     

    
      	 	
              k)

            	
              Section
                5.1(a)(iii)
                is
                hereby amended and restated in its entirety as
                follows:

            


    

     

    “(iii)
      from the date of achievement of Milestone 2 until March 31, 2008, Dow shall,
      at
      the request of MCEL, make available at a maximum one (1) FTE to use commercially
      reasonable efforts to (i) perform each of the incomplete Dow Consumer Tasks
      set
      forth in Section 5.2(f) and (i), respectively, and (ii) provide commercial
      and
      technical services from Dow’s current resources related to the characterization
      of chemicals, chemical processes, plastics, and plastic parts with respect
      to
      the then-applicable commercially reasonable efforts of Dow under Section 5.2;
      provided,
      however,
      that in
      no event will Dow be obligated to make available any FTEs after Dow has provided
      MCEL with a total of [***] person hours from the date of the achievement of
      Milestone 2.”

     

    
      	 	
              l)

            	
              Section
                5.2(d)
                and Section
                5.2(e)
                are hereby deleted in their
                entirety.

            


    

     

    
      	 	
              m)

            	
              Section
                5.2(i)
                is
                hereby amended and restated in its entirety as
                follows:

            


    

     

    “(i)
      Dow
      Consumer Tasks - Milestone 3.
      To the
      extent required by Section 5.1 above, from the date of achievement of Milestone
      2 until the achievement of the Consumer Objectives contained in Milestone 3,
      Dow
      Consumer Tasks shall include (i) assisting MCEL to develop the Consumer
      Prototype; and (ii) assisting MCEL in its identification and discussions with
      potential licensees.”

     

    
      	 	
              n)

            	
              Section
                5.2(j)
                is
                hereby deleted in its entirety.

            


    

     

    
      	 	
              o)

            	
              Section
                6.1(f)
                is
                hereby amended and restated in its entirety as
                follows:

            


    

     

    “(f)
      Upon
      Achievement of Milestone 3.
      Upon
      the achievement of Milestone 3, at the Fourth Closing (as defined in the Stock
      Purchase Agreement) MCEL shall issue to Dow, and Dow shall accept (subject
      to
      the terms of the Stock Purchase Agreement) such number of shares of Common
      Stock
      that equal the greater of: (i) a 1% Ownership Interest, or (ii) the number
      of
      shares of Common Stock that could be purchased for $250,000, based upon a
      per-share purchase price equal to the VWAP for the thirty (30)-trading day
      period immediately preceding the issuance thereof; provided,
      however,
      that
      the Company may, at its option, satisfy its obligations under this Section
      6.1(f) by paying to Dow an amount in cash equal to the value of such shares
      of
      Common Stock otherwise issuable pursuant to this Section 6.1(f), with such
      value
      to be determined based on the VWAP of the Common Stock for the thirty
      (30)-trading day period immediately preceding the date such shares would
      otherwise be issued.” 

     

    
      
         

      

      
        -3-

        
          

        

      

      
         

      

    

     

    
      	 	
              p)

            	
              Section
                6.1(g)
                is
                hereby deleted in its entirety.

            


    

     

    
      	 	
              q)

            	
              Section
                6.2(a)
                is
                hereby modified by deleting “or any Milestone” and substituting “Milestone
                1 or Milestone 2” therefor.

            


    

     

    
      	 	
              r)

            	
              Section
                6.2(b)
                is
                hereby modified by inserting “or Common Stock” after “any Series A
                Preferred Stock”.

            


    

     

    
      	 	
              s)

            	
              Section
                6.2(c) is hereby amended and restated in its entirety as
                follows:

            


    

     

    “Excess
      Shares.
      Subject
      to the terms of the Stock Purchase Agreement, if, at any time during the term
      of
      this Agreement, an issuance of Series A Preferred Stock or Series B Preferred
      Stock (or shares of Common Stock issuable upon conversion thereof or upon the
      exercise of Warrants) or Common Stock would result in Dow holding greater than
      a
      19.9% Ownership Interest in respect of Series A Preferred, Series B Preferred,
      Warrants and Common Stock acquired pursuant to the terms of the Stock Purchase
      Agreement, then the amount of Series A Preferred Stock, Series B Preferred
      Stock
      or Common Stock, as applicable, in excess of Dow’s 19.9% Ownership Interest (the
“Excess
      Shares”)
      shall
      be held in reserve by MCEL. Dow shall have the right, at any time and from
      time
      to time, when Dow’s Ownership Interest is less than 19.9%, to receive or
      purchase such Excess Shares, in whole or in part, upon the same terms and
      conditions that Dow would have received or purchased such Excess Shares at
      the
      time of the initial offering of such Excess Shares.”

     

    
      	 	
              t)

            	
              Section
                9.2
                is
                hereby deleted in its entirety.

            


    

     

    
      	 	
              u)

            	
              Section
                9.5(a)
                is
                hereby modified by deleting the words “, Milestone 3 or Milestone 4” and
                substituting “or Milestone 3”
therefor.

            


    

     

    
      	 	
              v)

            	
              Section
                11.4(ii)
                is
                hereby modified by (i) deleting the words “any Subsequent Closing (as
                defined in the Stock Purchase Agreement)” and substituting the words “the
                Second Closing or the Third Closing (each, as defined in the Stock
                Purchase Agreement)” therefor and (ii) deleting the words “such Subsequent
                Closing” and substituting the words “the Second Closing or the Third
                Closing, as applicable” therefor.

            


    

     

     

    
      
         

      

      
        -4-

        
          

        

      

      
         

      

    

     

     

    
      	 	
              w)

            	
              Section
                11.5(b)
                is
                hereby modified by inserting the words “or Common Stock” after “Series A
                Preferred Stock”.

            


    

     

    
      	 	
              x)

            	
              Section
                13.6
                is
                hereby modified by deleting the words “King & Spalding LLP, 1700
                Pennsylvania Ave, N.W., Washington, D.C. 20006, Attention: David
                Gibbons,
                Facsimile: 202.626.3737” and inserting the words “Covington & Burling
                LLP, 1201 Pennsylvania Avenue, N.W., Washington, DC 20004, Attention:
                David Engvall, Facsimile: 202.662.6000”
                therefor.

            


    

     

    
      	 	
              y)

            	
              Section
                13.7
                is
                hereby modified by deleting the word “Shares” and substituting the words
                “Preferred Shares” therefor.

            


    

     

    
      	 	
              z)

            	
              The
                defined term “Application”
                in Exhibit
                A
                is
                hereby amended and restated in its entirety as
                follows:

            


    

     

    “Application”
means
      (A) production of hydrogen gas by storing and chemically converting
      boron-hydride, alkali metal hydride, alkaline earth metal hydride, or
      aluminohydride fuel formulations into hydrogen by (1) controlling the contact
      of
      an alkaline aqueous boron hydride solution with a contained solid catalyst
      comprised of a transition metal adhered to a substrate which promotes the
      chemical reaction between the boron hydride and water to release hydrogen gas;
      and/or (2) [***];
      and/or (3) [***];
      and (B)
      interconnections and related control strategies for the integration of a fuel
      cell and hydrogen generator systems for delivery of hydrogen gas produced by
      one
      of these means for conversion to power by a fuel cell.”

     

    
      	 	
              aa)

            	
              The
                defined term “Dow
                Consumer Task”
                in Exhibit
                A
                is
                hereby modified by deleting the words “and 5.2(j)” and inserting the word
                “and” between “5.2(h)” and
“5.2(i).”

            


    

     

    
      	 	
              bb)

            	
              The
                defined term “Dow
                Military Task”
                in Exhibit
                A
                is
                hereby modified by deleting the words “, 5.2(d) and 5.2(e)” and inserting
                the word “and” between “5.2(b)” and
“5.2(c).”

            


    

     

    
      	 	
              cc)

            	
              The
                defined term “MCEL
                Consumer Task”
                in Exhibit
                A
                is
                hereby modified by deleting the words “and 4.2(j)” and inserting the word
                “and” between “4.2(h)” and
“4.2(i).”

            


    

     

    
      	 	
              dd)

            	
              The
                defined term “MCEL
                Military Task”
                in Exhibit
                A
                is
                hereby modified by deleting the words “, 4.2(d) and 4.2(e)” and inserting
                the word “and” between “4.2(b)” and
“4.2(c).”

            


    

     

    
      	 	
              ee)

            	
              The
                following defined term shall be added to Exhibit
                A:

            


    

     

     

    
      
         

      

      
        -5-

        
          

        

      

      
         

      

    

     

    “Sale
      or Merger”
means
      any of the following:

     

    (A) the
      merger, reorganization or consolidation of MCEL or such subsidiary or
      subsidiaries of MCEL the assets of which constitute all or substantially all
      the
      assets of the business of MCEL and its subsidiaries taken as a whole into or
      with another corporation, partnership, joint venture, limited liability company,
      or other entity, in which MCEL’s stockholders holding the right to vote
      generally in the election of directors, general partners, managing members
      or
      individuals holding similar positions (“MCEL’s
      Voting Power”)
      immediately preceding such merger, reorganization or consolidation (solely
      by
      virtue of their shares or other securities of MCEL or such subsidiaries) shall
      own less than fifty percent (50%) of the securities of the surviving
      corporation, partnership, joint venture, limited liability company, or other
      entity entitled to vote generally in the election of directors, general
      partners, managing members or individuals holding similar
      positions;

     

    (B) the
      sale,
      transfer or lease (but not including a transfer or lease by pledge or mortgage
      to a bona fide lender) of all or substantially all the assets of MCEL, whether
      pursuant to a single transaction or a series of related transactions or plan
      (which assets shall include for these purposes the assets of MCEL’s
      subsidiaries); or

     

    (C) the
      sale
      or transfer, whether in a single transaction or a series of related
      transactions, of securities of MCEL such that MCEL’s stockholders holding MCEL’s
      Voting Power immediately prior to such sale or transfer or series of transfers
      cease to hold a majority of MCEL’s Voting Power after such sale or transfer or
      series of transfers.”

     

    
      	 	
              ff)

            	
              The
                Milestone
                Table
                in
                Exhibit
                B
                is
                hereby modified by deleting the last two rows and adding a new last
                row
                beginning with “3” and containing the following text in its second
                column:

            


    

     

    “Milestone
      3 will be achieved upon the occurrence of the Consumer Objective set forth
      in
      either subsection (a) or (b) below:

     

    
      	
            	(a)	
              Development
                of a solid state hydrogen generation system (Solid State HODTM) prototype
                to demonstrate hydrogen storage capability which is adequate to address
                significant consumer electronics markets;
                or

            


    

     

    
      	
            	(b)	
              Secure
                a relationship with a consumer electronics OEM that has over $500
                million
                in revenues with capability to commercialize Solid State HODTM products.”
                

            


    

     

    
      	
            	3)	
              The
                Company hereby irrevocably waives its right to terminate the JDA
                pursuant
                to Section
                11.4(ii)
                of
                the JDA as a result of TDCC’s failure to make a Minimum Series B
                Investment (as defined in the JDA) in connection with the achievement
                of
                Milestone 2 (as defined in the JDA).


            


    

     

     

    
      
         

      

      
        -6-

        
          

        

      

      
         

      

    

     

    Stock
      Purchase Agreement

     

    
      	
            	4)	
              Pursuant
                to Section 9.9 of the SPA, TDCC and the Company hereby consent to
                amend
                the SPA, and the SPA is hereby amended, as
                follows:

            


    

     

    
      	 	
              a)

            	
              The
                fourth “WHEREAS”
                clause is hereby amended by (i) deleting “, 3 and 4” and substituting “and
                3” therefor and (ii) inserting “or Common Stock” after “Series A
                Preferred”.

            


    

     

    
      	 	
              b)

            	
              Section
                1.3(c)
                is
                hereby amended by adding the words “provided,
                further,
                that the number of shares of Series A2-2 Preferred issued at the
                Third
                Closing shall
                be
                reduced to the extent necessary so that such issuance does not result
                in
                result in the Purchaser beneficially owning (as determined in accordance
                with Rule 13d-3 under the Exchange Act) in excess of 9.9% of the
                outstanding Common Stock (as determined in accordance with Rule 13d-3
                under the Exchange Act)”.

            


    

     

    
      	 	
              c)

            	
              Section
                1.4(a)
                is
                amended and restated in its entirety as
                follows:

            


    

     

    the
      Company shall issue to the Purchaser, and the Purchaser may choose to accept
      (at
      its sole discretion, subject to Section
      1.8
      and
Section
      1.9),
      a
      number of shares of Common Stock equal to the greater of: (i) a 1% Ownership
      Interest, or (ii) the number of shares of Common Stock that could be purchased
      for $250,000, based upon a per-share purchase price equal to the VWAP of the
      Common Stock for the thirty (30)-trading day period immediately preceding the
      issuance thereof, but not in any event to exceed a maximum 2% Ownership
      Interest; provided,
      however,
      that
      the Company may, at its option, satisfy its obligations under this Section
      1.4(a)
      by
      paying to the Purchaser an amount in cash equal to the value of such shares
      of
      Common Stock otherwise issuable pursuant to this Section
      1.4(a),
      with
      such value to be determined based on the VWAP of the Common Stock for the thirty
      (30)-trading day period immediately preceding the date such shares would
      otherwise be issued; provided further
      that if
      the Company proposes to satisfy its obligations under this Section 1.4(a) by
      issuing shares of Common Stock to TDCC, if and to the extent that such issuance
      would result in the Purchaser beneficially owning (as determined in accordance
      with Rule 13d-3 under the Exchange Act) in excess of 9.9% of the outstanding
      Common Stock (as determined in accordance with Rule 13d-3 under the Exchange
      Act), the
      Company shall issue only such number of shares of Common Stock as does not
      cause
      Purchaser to beneficially own in excess of 9.9% of the outstanding Common Stock,
      and shall pay Purchaser an amount in cash equal to the value of the number
      of
      shares of Common Stock the issuance of which would cause Purchaser to
      beneficially own in excess of 9.9% of the outstanding Common Stock, with such
      value to be determined based on the VWAP of the Common Stock for the thirty
      (30)-trading day period immediately preceding the applicable issuance of Common
      Stock.”

     

    
      
         

      

      
        -7-

        
          

        

      

      
         

      

    

     

    
      	 	
              d)

            	
              Section
                1.4(b),
                Section
                1.4(c),
                and Section
                1.5
                are hereby deleted in their
                entirety.

            


    

     

    
      	 	
              e)

            	
              Section
                1.6
                is
                hereby modified by (i) deleting the words “and the Fifth Closing”, (ii)
                inserting the word “and” immediately after the words “the Third Closing”,
                (iii) deleting the words “and the Fifth Closing Date”, (iv) inserting the
                word “and” immediately after the words “the Third Closing Date” and (v)
                deleting the words “King & Spalding LLP, 1700 Pennsylvania Avenue,
                N.W., Washington, DC 20006” and substituting “Covington & Burling LLP,
                1201 Pennsylvania Avenue, N.W., Washington, DC 20004”
                therefor.

            


    

     

    
      	 	
              f)

            	
              Section
                1.7
                is
                hereby modified by deleting the words “the Fourth Closing or the Fifth
                Closing” and by inserting the word “or” immediately after the words “the
                Second Closing”.

            


    

     

    
      	 	
              g)

            	
              Section
                1.8
                is
                hereby modified by inserting “or Common Stock” after “any Series A
                Preferred”.

            


    

     

    
      	 	
              h)

            	
              Section
                1.9
                is
                hereby amended and restated in its entirety as
                follows:

            


    

     

    “Excess
      Shares.
      If, at
      any time during the term of this Agreement, an issuance of Preferred Shares
      (or
      shares of Common Stock issuable upon conversion thereof or upon the exercise
      of
      Warrants) or shares of Common Stock in accordance with this Section
      1
      would
      result in the Purchaser owning greater than a 19.9% Ownership Interest in
      respect of Series A Preferred, Series B Preferred, Warrants and Common Stock
      acquired pursuant to the terms of this Agreement, then the amount of Preferred
      Shares or shares of Common Stock, as applicable, in excess of the Purchaser’s
      19.9% Ownership Interest (the “Excess
      Shares”)
      shall
      be held in reserve by the Company. The Purchaser shall have the right, at any
      time and from time to time, when the Purchaser’s Ownership Interest is less than
      19.9%, to receive or purchase such Excess Shares, in whole or in part, upon
      the
      same terms and conditions that the Purchaser would have received or purchased
      such Excess Shares at the time of the initial offering of such Excess Shares;
      provided, however, that in no event shall the Purchaser be entitled to receive
      or purchase Excess Shares pursuant to this Section 1.9 in an amount that, by
      virtue of such receipt or purchase, would result in the Purchaser owning greater
      than a 19.9% Ownership Interest in respect of Series A Preferred, Series B
      Preferred, Warrants, and Common Stock acquired pursuant to the terms of this
      Agreement.”

     

    
      	 	
              i)

            	
              The
                following defined term is hereby added to Section
                1.10:

            


    

     

    “Exchange
      Act”
means
      the Securities Exchange
      Act
      of 1934,
      as amended.

     

    
      
         

      

      
        -8-

        
          

        

      

      
         

      

    

     

    
      	 	
              j)

            	
              The
                defined term “Milestone
                Target Payment Date”
                in Section
                1.10
                is
                hereby modified by deleting the last row of the table contained
                therein.

            


    

     

    
      	 	
              k)

            	
              Section
                4.1
                is
                hereby modified by deleting the word “or” and inserting “, or Common
                Stock,” after “Warrants”.

            


    

     

    
      	 	
              l)

            	
              Section
                4.2
                is
                hereby deleted in its entirety.

            


    

     

    
      	 	
              m)

            	
              Section
                4.6(a)
                is
                hereby deleted in its entirety.

            


    

     

    
      	 	
              n)

            	
              Section
                4.10(a)
                is
                hereby modified by deleting the words “, Milestone 3 and Milestone 4” and
                substituting the words “and Milestone 3”
                therefor.

            


    

     

    
      	 	
              o)

            	
              Section
                7.2(a)
                is
                hereby modified by deleting the words “Fifth Closing” and substituting the
                words “Fourth Closing” therefor.

            


    

     

    
      	 	
              p)

            	
              Section
                7.2(f)
                is
                hereby modified by deleting the words “Fifth Closing” and substituting the
                words “Fourth Closing” therefor.

            


    

     

    
      	 	
              q)

            	
              Section
                7.2(g)
                is
                hereby modified by deleting the words “Fifth Closing” and substituting the
                words “Fourth Closing” therefor.

            


    

     

    
      	 	
              r)

            	
              Section
                7.2(h)
                is
                hereby modified by deleting the words “any Subsequent Closing” and
                substituting “the Second Closing or the Third Closing”
                therefor.

            


    

     

    
      	 	
              s)

            	
              Section
                7.3(b)
                is
                hereby modified by (i) inserting the words “or Common Stock” after “Series
                A Preferred” in clause (i)(b) and (ii) inserting the words “or Common
                Stock” after “Preferred Shares” in clause
                (ii).

            


    

     

    
      	 	
              t)

            	
              Section
                9.6
                is
                hereby modified by deleting the words “King & Spalding LLP, 1700
                Pennsylvania Ave, N.W., Washington, D.C. 20006, Attention: David
                Gibbons,
                Facsimile: 202.626.3737” and inserting the words “Covington & Burling
                LLP, 1201 Pennsylvania Avenue, N.W., Washington, DC 20004, Attention:
                David Engvall, Facsimile: 202.662.6000”
                therefor.

            


    

     

    
      	 	
              u)

            	
              Section
                9.9
                is
                hereby modified by deleting the word “Shares” and substituting the words
                “Preferred Shares” therefor.

            


    

     

    
      	
            	5)	
              The
                Company hereby irrevocably waives its right to terminate the SPA
                pursuant
                to Section
                7.2(h)
                of
                the SPA as a result of TDCC’s failure to make a Minimum Series B
                Investment (as defined in the SPA) in connection with the achievement
                of
                Milestone 2. 

            


    

     

    Investor
      Rights Agreement

     

    
      	
            	6)	
              TDCC
                and the Company agree that the IRA is hereby terminated pursuant
                to
                Section 5.7 thereof, effective as of the date hereof.
                

            


    

     

     

    
      
         

      

      
        -9-

        
          

        

      

      
         

      

    

     

    Registration
      Rights Agreement

     

    
      	
            	7)	
              Pursuant
                to Section 5.5 of the RRA, TDCC and the Company hereby consent to
                amend
                the RRA, and the RRA is hereby amended, as
                follows:

            


    

     

    
      	 	
              a)

            	
              The
                defined term “Registrable
                Securities”
                in Section
                1
                is
                hereby modified by deleting the word “or” immediately preceding subsection
                (ii) and inserting the following after the words “clause (i)
                above”:

            


    

     

    “or
      (iii)
      the Fourth Closing (as such term is defined in the Purchase
      Agreement),”

     

    
      	 	
              b)

            	
              The
                defined term “Special
                Counsel”
                in Section
                1
                is
                hereby modified by deleting the words “King & Spalding LLP” and
                substituting the words “Covington & Burling LLP”
                therefor.

            


    

     

    
      	 	
              c)

            	
              Section
                5.4
                is
                hereby modified by deleting the words “King & Spalding LLP, 1700
                Pennsylvania Ave, N.W., Washington, D.C. 20006, Attention: David
                Gibbons,
                Facsimile: 202.626.3737” and inserting the words “Covington & Burling
                LLP, 1201 Pennsylvania Avenue, N.W., Washington, DC 20004, Attention:
                David Engvall, Facsimile: 202.662.6000”
                therefor.

            


    

     

    Letter
      Agreement

     

    
      	
            	8)	
              TDCC
                and the Company hereby consent to amend the Letter Agreement, and
                the
                Letter Agreement is hereby amended, as
                follows:

            


    

     

    
      	 	
              a)

            	
              Section
                1
                is
                hereby amended and restated in its entirety as
                follows:

            


    

     

    “1.
       Notwithstanding
      anything contained in the Series B Certificate, The Dow Chemical Company
      (“TDCC”),
      hereby irrevocably waives any right to any adjustment to the Applicable
      Conversion Price pursuant to the provisions contained in Section d(7) thereof
      as
      a result of any event that occurs on or after July 25, 2007, provided,
      however,
      that,
      notwithstanding the foregoing, TDCC and the Company hereby agree that, as of
      July 25, 2007 and at all times thereafter, in the event the Company issues
      any
      Additional Shares of Common Stock (as
      defined in the Series B Certificate)
      following July 25, 2007, at a per share consideration less than the Series
      B-1
      Conversion Price (as defined in the Series B Certificate) then in effect, then
      the Series B-1 Conversion Price shall be reduced, concurrently with such
      issuance, to a price (calculated to the nearest cent) determined by multiplying
      such Series B-1 Conversion Price by a fraction:

     

    (A)
      the
      numerator of which shall be the number of shares of Common Stock (as defined
      in
      the Series B Certificate) outstanding immediately prior to such issuance plus
      the number of shares of Common Stock issuable upon conversion of all Common
      Stock Equivalents (as defined in the Series B Certificate) outstanding
      immediately prior to such issuance plus the number of shares of Common Stock
      which the aggregate consideration received by the Company for the total number
      of Additional Shares of Common Stock in such issuance would purchase at the
      Series B-1 Conversion Price in effect immediately prior to such issuance; and
      

     

    
      
         

      

      
        -10-

        
          

        

      

      
         

      

    

     

    (B)
      the
      denominator of which shall be the number of shares of Common Stock outstanding
      immediately prior to such issuance plus the number of shares of Common Stock
      issuable upon conversion of all Common Stock Equivalents outstanding immediately
      prior to such issuance plus the number of such Additional Shares of Common
      Stock
      so issued.”

     

    Waiver
      of Series A2 Anti-dilution protection

     

    
      	
            	9)	
              Notwithstanding
                anything contained in the Series A2 Certificate, TDCC hereby irrevocably
                waives any right to any adjustment to the Series A2-2 Conversion
                Price (as
                defined in the Series A2 Certificate) pursuant to the provisions
                contained
                in Section d(7)(iii) thereof as a result of any event that occurs
                on or
                   after July 25], 2007, provided,
                however,
                that TDCC and the Company hereby agree that as of July 25, 2007 and
                at all
                times thereafter, in the event the Company issues any Additional
                Shares of
                Common Stock (as
                defined in the Series A2 Certificate)
                following July 25, 2007, at a per share consideration less than the
                Series
                A2-2 Conversion Price (as
                defined in the Series A2 Certificate)
                then in effect, then the Series A2-2 Conversion Price shall be reduced,
                concurrently with such issuance, to a price (calculated to the nearest
                cent) determined by multiplying such Series A2-2 Conversion Price
                by a
                fraction:

            


    

     

    (A)
      the
      numerator of which shall be the number of shares of Common Stock outstanding
      immediately prior to such issuance plus the number of shares of Common Stock
      issuable upon conversion of all Common Stock Equivalents (as defined in the
      Series A2 Certificate) outstanding immediately prior to such issuance plus
      the
      number of shares of Common Stock which the aggregate consideration received
      by
      the Company for the total number of Additional Shares of Common Stock in such
      issuance would purchase at the Series A2-2 Conversion Price in effect
      immediately prior to such issuance; and 

     

    (B)
      the
      denominator of which shall be the number of shares of Common Stock outstanding
      immediately prior to such issuance plus the number of shares of Common Stock
      issuable upon conversion of all Common Stock Equivalents outstanding immediately
      prior to such issuance plus the number of such Additional Shares of Common
      Stock
      so issued.

     

    
      	
            	10)	
              TDCC
                hereby agrees that it will not sell, transfer or otherwise dispose
                of any
                shares of Series A2-2 Preferred Stock unless the transferee expressly
                assumes this agreement in connection with such sale, transfer or
                disposition.

            


    

     

     

    
      
         

      

      
        -11-

        
          

        

      

      
         

      

    

     

    Except
      as
      specifically amended by this letter agreement, each of the JDA, SPA, RRA and
      Letter Agreement shall continue in full force and effect in accordance with
      their respective terms.

     

    The
      execution and delivery by the Company of this letter agreement and compliance
      by
      the Company with the provisions hereof do not and will not (a) conflict
      with or result in a breach of the certificate of incorporation, bylaws of the
      Company, (b) violate any agreement to which the Company is a party, or (c)
      require the consent or approval of any third party.

     

    This
      letter agreement may be executed in one or more counterparts, each of which,
      when executed and delivered, shall be an original, but all of which together
      shall constitute but one and the same instrument. This letter agreement may
      also
      be executed via facsimile, which shall be deemed to be an original.

     

    This
      letter agreement shall be governed by and construed in accordance with the
      laws
      of the State of Delaware without regard to its principles of conflicts of
      laws.

    


    The
      parties agree that the remedy at law for any breach of this letter agreement
      may
      be inadequate, and that, as among TDCC and the Company, any party by whom this
      letter agreement is enforceable shall be entitled to specific performance in
      addition to any other appropriate relief or remedy. Such party may, in its
      sole
      discretion, apply to a court of competent jurisdiction for specific performance
      or injunctive or such other relief as such court may deem just and proper in
      order to enforce this agreement as among TDCC and the Company, or prevent any
      violation hereof, and, to the extent permitted by applicable law, as among
      TDCC
      and the Company, each party waives any objection to the imposition of such
      relief.


    


    [Signature
      page follows]

     

    
      
         

      

      
        -12-

        
          

        

      

      
         

      

    


    Please
      sign in the space provided below and return a copy to the undersigned to confirm
      your agreement to the foregoing. 

     

    
      	 	 	 
	 	
              Very
                truly yours

               

              MILLENNIUM
                CELL INC.

            
	 
 	 
 	 
 
	
            	By:  	/s/ John D. Giolli
	 	
              

              Name:
                John D. Giolli, CPA

            
	 	
              Title:
                Chief Financial Officer

            


    

     

     

    
      	
              Agreed
                to and acknowledged:

               

              THE
                DOW CHEMICAL COMPANY

            	 	 	 
	 	 	 	 
	 	 	 	 
	By: /s/
              James H. Plonka	 	 	
            
	
              
                

              

              Name:
                James H. Plonka

            	 	 	
            
	
              Title:
                Authorized Representative