AMENDED
      AND RESTATED REVOLVING PROMISSORY NOTE

     

    $2,300,000.00    December
      __, 2006

     

    FOR
      VALUE
      RECEIVED, LIGHTING SCIENCE GROUP CORPORATION, a Delaware corporation (whether
      one or more, “Borrower”),
      having an address at 2100 McKinney Ave., Suite 1555, Dallas, Texas 75201, hereby
      promises to pay to the order of BANK OF TEXAS, N.A., a national banking
      association (together with its successors and assigns and any subsequent holders
      of this Promissory Note, the “Lender”),
      as
      hereinafter provided, the principal sum of TWO MILLION THREE HUNDRED THOUSAND
      AND NO/100 DOLLARS ($2,300,000.00) or so much thereof as may be advanced by
      Lender from time to time hereunder to or for the benefit or account of Borrower,
      together with interest thereon at the Note Rate (as hereinafter defined), and
      otherwise in strict accordance with the terms and provisions
      hereof.

     

    ARTICLE
      I  

     

    DEFINITIONS

     

    Section
      1.1  Definitions.
      As used
      in this Promissory Note, the following terms shall have the following
      meanings:

     

    Applicable
      Margin:
      One
      percent (1%).

     

    Applicable
      Rate:
      The
      Base Rate plus the Applicable Margin.

     

    Base
      Rate:
      For any
      day, a rate of interest equal to the Prime Rate for such day.

     

    Charges:
      All
      fees, charges and/or any other things of value, if any, contracted for, charged,
      taken, received or reserved by Lender in connection with the transactions
      relating to this Note and the other Loan Documents, which are treated as
      interest under applicable law.

     

    Default
      Interest Rate:
      A rate
      per annum equal to the Note Rate plus four percent (4%), but in no event in
      excess of the Maximum Lawful Rate.

     

    Event
      of Default:
      Any
      event or occurrence described under Section
      3.1
      hereof.

     

    Loan
      Agreement:
      The
      certain Loan Agreement dated June 29, 2006 between Borrower and Lender, as
      amended of even date herewith and as may be further amended from time to
      time.

     

    Loan
      Documents:
      As
      defined in the Loan Agreement.

     

    Maturity
      Date:
      June
      28, 2007.

     

    Maximum
      Lawful Rate:
      The
      maximum lawful rate of interest which may be contracted for, charged, taken,
      received or reserved by Lender in accordance with the applicable laws of the
      State of Texas (or applicable United States federal law to the extent that
      such
      law permits Lender to contract for, charge, take, receive or reserve a greater
      amount of interest than under Texas law), taking into account all Charges made
      in connection with the transaction evidenced by this Note and the other Loan
      Documents.

     

    
      Dallas
        1193263_1 4827.85
Note:
      This
      Promissory Note, as may be amended from time to time.

     

    Note
      Rate:
      The
      rate equal to the lesser of (a) the Maximum Lawful Rate or (b) the Applicable
      Rate.

     

    Payment
      Date:
      The
      earlier of the 30th
      day and
      last day of each and every calendar month during the term of this
      Note.

     

    Prime
      Rate:
      The
      rate of interest set by BOK Financial Corporation, in its sole discretion,
      on a
      daily basis as published by BOK Financial Corporation from time to time, which
      Borrower hereby acknowledges and agrees may not be the lowest interest rate
      charged by Lender, and which rate shall change as said prime rate
      changes.

     

    Any
      capitalized term used in this Note and not otherwise defined herein shall have
      the meaning ascribed to each such term in the Loan Agreement. All terms used
      herein, whether or not defined in Section
      1.1
      hereof,
      and whether used in singular or plural form, shall be deemed to refer to the
      object of such term whether such is singular or plural in nature, as the context
      may suggest or require.

     

    ARTICLE
      II  

     

    PAYMENT
      TERMS

     

    Section
      2.1  Payment
      of Principal and Interest.
      All
      accrued but unpaid interest on the principal balance of this Note outstanding
      from time to time shall be due and payable on each Payment Date, commencing
      on
      December 30, 2006. The then-outstanding principal balance of this Note and
      all
      accrued but unpaid interest thereon shall be due and payable on the Maturity
      Date or upon the earlier maturity hereof, whether by acceleration or otherwise.
      Borrower may from time to time during the term of this Note borrow, partially
      or
      wholly repay its outstanding borrowings, and reborrow, subject to all of the
      limitations, terms and conditions of this Note and of the Loan Documents;
      provided however, that the total outstanding borrowings under this Note shall
      not at any time exceed the Borrowing Base or the principal amount stated above.
      The unpaid principal balance of this Note at any time shall be the total amounts
      advanced hereunder by Lender less the amount of principal payments made hereon
      by or for Borrower, which balance may be endorsed hereon from time to time
      by
      Lender or otherwise noted in Lender’s records, which notations shall be, absent
      manifest error, conclusive evidence of the amounts owing hereunder from time
      to
      time.

     

    Section
      2.2  Application.
      Except
      as expressly provided herein to the contrary, all payments on this Note shall
      be
      applied in the following order of priority: (i) the payment or reimbursement
      of
      any expenses, costs or obligations (other than the outstanding principal balance
      hereof and interest hereon) for which either Borrower shall be obligated or
      Lender shall be entitled pursuant to the provisions of this Note or the other
      Loan Documents, (ii) the payment of accrued but unpaid interest hereon, and
      (iii) the payment of all or any portion of the principal balance hereof then
      outstanding hereunder. If an Event of Default exists under this Note or under
      any of the other Loan Documents, then Lender may, at the sole option of Lender,
      apply any such payments, at any time and from time to time, to any of the items
      specified in clauses (i), (ii) or (iii) above without regard to the order of
      priority otherwise specified in this Section
      2.

     

    Section
      2.3  Payments.
      All
      payments under this Note made to Lender shall be made in immediately available
      funds at 4217 Swiss Avenue, Dallas, Texas 75204 (or at such other place as
      Lender, in Lender’s sole discretion, may have established by delivery of written
      notice thereof to Borrower from time to time), without offset, in lawful money
      of the United States of America, which shall at the time of payment be legal
      tender in payment of all debts and dues, public and private. Payments by check
      or draft shall not constitute payment in immediately available funds until
      the
      required amount is actually received by Lender in full. Payments in immediately
      available funds received by Lender in the place designated for payment on a
      Business Day prior to 11:00 a.m. Dallas, Texas time at said place of payment
      shall be credited prior to the close of business on the Business Day received,
      while payments received by Lender on a day other than a Business Day or after
      11:00 a.m. Dallas, Texas time on a Business Day shall not be credited until
      the
      next succeeding Business Day. If any payment of principal or interest on this
      Note shall become due and payable on a day other than a Business Day, such
      payment shall be made on the next succeeding Business Day. Any such extension
      of
      time for payment shall be included in computing interest which has accrued
      and
      shall be payable in connection with such payment.

     

    Section
      2.4  Computation
      Period.
      Interest on the indebtedness evidenced by this Note shall be computed on the
      basis of a three hundred sixty (360) day year and shall accrue on the actual
      number of days elapsed for any whole or partial month in which interest is
      being
      calculated. In computing the number of days during which interest accrues,
      the
      day on which funds are initially advanced shall be included regardless of the
      time of day such advance is made, and the day on which funds are repaid shall
      be
      included unless repayment is credited prior to the close of business on the
      Business Day received as provided in Section
      2.3
      hereof.

     

    Section
      2.5  Prepayment.
      Borrower shall have the right to prepay, at any time and from time to time,
      upon
      five (5) days prior written notice to Lender, without fee, premium or penalty
      (except as noted below), all or any portion of the outstanding principal balance
      hereof, provided, however, that such prepayment shall also include any and
      all
      accrued but unpaid interest on the amount of principal being so prepaid through
      and including the date of prepayment, plus any other sums which have become
      due
      to Lender under the other Loan Documents on or before the date of prepayment,
      but which have not been fully paid. If at any time the outstanding principal
      balance hereunder exceeds
      the Borrowing Limit, Borrower shall immediately
      upon
      written notice of demand prepay
      such principal balance to the extent necessary to eliminate such excess;
      provided, that if such excess is directly caused by a default of one or more
      Guarantors under a Guaranty Agreement or other Loan Document and the amount
      of
      such excess is less than $350,000.00, Borrower shall have thirty (30) days
      from
      the date of such notice to pay such excess amount or cause the replacement
      of
      the defaulting Guarantor with another Guarantor subject to documents and terms
      satisfactory to Lender.

     

    Section
      2.6  Unconditional
      Payment.
      Borrower is and shall be obligated to pay all principal, interest and any and
      all other amounts which become payable under this Note or under any of the
      other
      Loan Documents absolutely and unconditionally and without any abatement,
      postponement, diminution or deduction whatsoever and without
      any
      reduction for counterclaim or setoff whatsoever. If at any time any payment
      received by Lender hereunder shall be deemed by a court of competent
      jurisdiction to have been a voidable preference or fraudulent conveyance under
      any Debtor Relief Laws, then the obligation to make such payment shall survive
      any cancellation or satisfaction of this Note or return thereof to Borrower
      and
      shall not be discharged or satisfied with any prior payment thereof or
      cancellation of this Note, but shall remain a valid and binding obligation
      enforceable in accordance with the terms and provisions hereof, and such payment
      shall be immediately due and payable upon demand.

     

    Section
      2.7  Partial
      or Incomplete Payments.
      Remittances in payment of any part of this Note other than in the required
      amount in immediately available funds at the place where this Note is payable
      shall not, regardless of any receipt or credit issued therefor, constitute
      payment until the required amount is actually received by Lender in full in
      accordance herewith and shall be made and accepted subject to the condition
      that
      any check or draft may be handled for collection in accordance with the practice
      of the collecting bank or banks. Acceptance by Lender of any payment in an
      amount less than the full amount then due shall be deemed an acceptance on
      account only, and the failure to pay the entire amount then due shall be and
      continue to be an Event of Default in the payment of this Note.

     

    Section
      2.8  Default
      Interest Rate, Etc.
      Upon
      the occurrence of a default or Event of Default under any of the Loan Documents,
      and for so long as such default or Event of Default exists, regardless of
      whether or not there has been an acceleration of the indebtedness evidenced
      by
      this Note, and at all times after the maturity of the indebtedness evidenced
      by
      this Note (whether by acceleration or otherwise), and in addition to all other
      rights and remedies of Lender hereunder, interest shall accrue on the
      outstanding principal balance hereof at the Default Interest Rate, and such
      accrued interest shall be immediately due and payable. Borrower acknowledges
      that it would be extremely difficult or impracticable to determine Lender’s
      actual damages resulting from any late payment or Event of Default, and such
      late charges and accrued interest are reasonable estimates of those damages
      and
      do not constitute a penalty. 

     

    ARTICLE
      III  

     

    EVENT
      OF DEFAULT AND REMEDIES

     

    Section
      3.1  Event
      of Default.
      The
      occurrence or happening, at any time and from time to time, of any one or more
      of the following shall immediately constitute an “Event
      of Default”
under
      this Note: (a) Borrower shall fail, refuse or neglect to pay and satisfy, in
      full and in the applicable method and manner required, any required payment
      of
      principal or interest or any other portion of the indebtedness evidenced by
      this
      Note,
      within
      five (5) days of the date the same shall become due and
      payable, whether at the stipulated due date thereof, at a date fixed for
      payment, or at maturity, by acceleration or otherwise; or (b) the occurrence
      of
      any default under this Note or the occurrence of any Event of Default as defined
      in or under the Loan Agreement or any other Loan Document that remains uncured
      under and pursuant to the provisions of the Loan Agreement or any other Loan
      Document.

     

    Section
      3.2  Remedies.
      Upon
      the occurrence of an Event of Default, Lender shall have the immediate right,
      at
      the sole discretion of Lender and without notice, demand, presentment, notice
      of
      nonpayment or nonperformance, protest, notice of protest, notice of intent
      to
      accelerate, notice of acceleration, or any other notice or any other action
      (ALL
      OF WHICH BORROWER HEREBY EXPRESSLY WAIVES AND RELINQUISHES)
      (i) to
      declare the entire unpaid balance of the indebtedness evidenced by this Note
      (including, without limitation, the outstanding principal balance hereof,
      including all sums advanced or accrued hereunder or under any other Loan
      Document, and all accrued but unpaid interest thereon) at once immediately
      due
      and payable (and upon such declaration, the same shall be at once immediately
      due and payable) and may be collected forthwith, whether or not there has been
      a
      prior demand for payment and regardless of the stipulated date of maturity,
      and
      (ii) to exercise any and all other rights and remedies available to the Lender
      in law or in equity, under the Loan Documents or otherwise.

     

    ARTICLE
      IV  

     

    GENERAL
      PROVISIONS

     

    Section
      4.1  No
      Waiver; Amendment.
      The
      failure to exercise any remedy available to Lender shall not be deemed to be
      a
      waiver of any rights or remedies of Lender under this Note or under any of
      the
      other Loan Documents, or at law or in equity. No extension of the time for
      the
      payment of this Note or any installment due hereunder, made by agreement with
      any person now or hereafter liable for the payment of this Note, shall operate
      to release, discharge, modify, change or affect the original liability of
      Borrower under this Note, either in whole or in part, unless Lender
      specifically, unequivocally and expressly agrees otherwise in writing. This
      Note
      may not be changed orally, but only by an agreement in writing signed by the
      party against whom enforcement of any waiver, change, or modification is
      sought.

     

    Section
      4.2  Interest
      Provisions.
      The
      provisions of Section 11.6 and 11.7 of the Loan Agreement are hereby
      incorporated by reference and shall apply to this Note as if fully set forth
      herein.

     

    Section
      4.3  Further
      Assurances and Corrections.
      From
      time to time, at the request of Lender, Borrower will (a) promptly correct
      any
      defect, error or omission which may be discovered in the contents of this Note
      or in any other Loan Document or in the execution or acknowledgment thereof;
      and
      (b) execute, acknowledge, deliver, record and/or file (or cause to be executed,
      acknowledged, delivered, recorded and/or filed) such further documents and
      instruments and perform such further acts and provide such further assurances
      as
      may be necessary, desirable, or proper, in Lender’s reasonable
      opinion.

     

    Section
      4.4  Governing
      Law.
      This
      Note is executed and delivered as an incident to a lending transaction
      negotiated and consummated in Dallas County, Texas, and shall be governed by
      and
      construed in accordance with the laws of the State of Texas. Borrower, for
      itself and its successors and assigns, hereby irrevocably (i) submits to the
      nonexclusive jurisdiction of the state and federal courts in Texas, (ii) waives,
      to the fullest extent permitted by law, any objection that it may now or in
      the
      future have to the laying of venue of any litigation arising out of or in
      connection with this Note or any Loan Document brought in the District Court
      of
      Dallas County, Texas, or in the United States District Court for the Northern
      District of Texas, Dallas Division, (iii) waives any objection it may now or
      hereafter have as to the venue of any such action or proceeding brought in
      such
      court or that such court is an inconvenient forum, and (iv) agrees that any
      legal proceeding against any party to any of the Loan Documents arising out
      of
      or in connection with any of the Loan Documents may be brought in one of the
      foregoing courts. Borrower hereby agrees that service of process upon Borrower
      may be made by certified or registered mail, return receipt requested, at its
      address specified herein. Nothing herein shall affect the right of Lender to
      serve process in any other manner permitted by law or shall limit the right
      of
      Lender to bring any action or proceeding against Borrower or with respect to
      any
      of Borrower’s property in courts in other jurisdictions. The scope of each of
      the foregoing waivers is intended to be all encompassing of any and all disputes
      that may be filed in any court and that relate to the subject matter of this
      transaction, including, without limitation, contract claims, tort claims, breach
      of duty claims, and all other common law and statutory claims. Borrower
      acknowledges that these waivers are a material inducement to Lender’s agreement
      to enter into the agreements and obligations evidenced by the Loan Documents,
      that Lender has already relied on these waivers and will continue to rely on
      each of these waivers in related future dealings. The waivers in this
Section
      4.4
      are
      irrevocable, meaning that they may not be modified either orally or in writing,
      and these waivers apply to any future renewals, extensions, amendments,
      modifications, or replacements in respect of any and all of the applicable
      Loan
      Documents. In connection with any litigation, this Note may be filed as a
      written consent to a trial by the court.

     

    Section
      4.5  Waiver
      of Jury Trial.
      BORROWER, TO THE FULLEST EXTENT PERMITTED BY APPLICABLE LAW, HEREBY KNOWINGLY,
      INTENTIONALLY, IRREVOCABLY, UNCONDITIONALLY AND VOLUNTARILY, WITH AND UPON
      THE
      ADVICE OF COMPETENT COUNSEL, WAIVES, RELINQUISHES AND FOREVER FORGOES THE RIGHT
      TO A TRIAL BY JURY IN ANY ACTION OR PROCEEDING BASED UPON, ARISING OUT OF,
      OR IN
      ANY WAY RELATING TO THIS NOTE OR ANY CONDUCT, ACT OR OMISSION OF LENDER OR
      BORROWER, OR ANY OF THEIR DIRECTORS, OFFICERS, PARTNERS, MEMBERS, EMPLOYEES,
      AGENTS OR ATTORNEYS, OR ANY OTHER PERSONS AFFILIATED WITH LENDER OR BORROWER,
      IN
      EACH OF THE FOREGOING CASES, WHETHER SOUNDING IN CONTRACT, TORT OR
      OTHERWISE.

     

    Section
      4.6  Successors
      and Assigns.
      The
      terms and provisions hereof shall be binding upon and inure to the benefit
      of
      Borrower and Lender and their respective heirs, executors, legal
      representatives, successors, successors-in-title and assigns, whether by
      voluntary action of the parties, by operation of law or otherwise, and all
      other
      persons claiming by, through or under them. The terms “Borrower” and “Lender” as
      used hereunder shall be deemed to include their respective heirs, executors,
      legal representatives, successors, successors-in-title and assigns, whether
      by
      voluntary action of the parties, by operation of law or otherwise, and all
      other
      persons claiming by, through or under them. Borrower’s rights and obligations
      hereunder may not be assigned or otherwise transferred without the prior written
      consent of Lender.

     

    Section
      4.7  Controlling
      Agreement.
      In the
      event of any conflict between the provisions of this Note and the Loan
      Agreement, it is the intent of the parties hereto that the provisions of the
      Loan Agreement shall control. In the event of any conflict between the
      provisions of this Note and any of the other Loan Documents (other than the
      Loan
      Agreement), it is the intent of the parties hereto that the provisions of this
      Note shall control. The parties hereto acknowledge that they were represented
      by
      competent counsel in connection with the negotiation, drafting and execution
      of
      this Note and the other Loan Documents and that this Note and the other Loan
      Documents shall not be subject to the principle of construing their meaning
      against the party which drafted same.

     

    Section
      4.8  Notices.
      All
      notices or other communications required or permitted to be given pursuant
      to
      this Note shall be in writing and given as set forth in the Loan
      Agreement.

     

    Section
      4.9  Severability.
      If any
      provision of this Note or the application thereof to any person or circumstance
      shall, for any reason and to any extent, be invalid or unenforceable, then
      neither the remainder of this Note nor the application of such provision to
      other persons or circumstances nor the other instruments referred to herein
      shall be affected thereby, but rather shall be enforced to the greatest extent
      permitted by applicable law.

     

    Section
      4.10  Right
      of Setoff.
      In
      addition to all liens upon and rights of setoff against the money, securities,
      or other property of Borrower given to Lender that may exist under applicable
      law, Lender shall have and Borrower hereby grants to Lender a lien upon and
      a
      right of setoff against all money, securities, and other property of Borrower,
      now or hereafter in possession of or on deposit with Lender, whether held in
      a
      general or special account or deposit, for safe-keeping or otherwise, and every
      such lien and right of setoff may be exercised without demand upon or notice
      to
      Borrower. No lien or right of setoff shall be deemed to have been waived by
      any
      act or conduct on the part of Lender, or by any neglect to exercise such right
      of setoff or to enforce such lien, or by any delay in so doing, and every right
      of setoff and lien shall continue in full force and effect until such right
      of
      setoff or lien is specifically waived or released by an instrument in writing
      executed by Lender.

     

    Section
      4.11  Statement
      of Unpaid Balance.
      Intentionally left blank.

     

    Section
      4.12  Entire
      Agreement.
      THIS
      NOTE AND THE OTHER LOAN DOCUMENTS CONTAIN THE FINAL, ENTIRE AGREEMENT BETWEEN
      THE PARTIES HERETO RELATING TO THE SUBJECT MATTER HEREOF AND THEREOF AND ALL
      PRIOR AGREEMENTS, WHETHER WRITTEN OR ORAL, RELATIVE HERETO AND THERETO WHICH
      ARE
      NOT CONTAINED HEREIN OR THEREIN ARE SUPERSEDED AND TERMINATED HEREBY, AND THIS
      NOTE AND THE OTHER LOAN DOCUMENTS MAY NOT BE CONTRADICTED OR VARIED BY EVIDENCE
      OF PRIOR, CONTEMPORANEOUS OR SUBSEQUENT ORAL AGREEMENTS OR DISCUSSIONS OF THE
      PARTIES HERETO. THERE ARE NO UNWRITTEN ORAL AGREEMENTS AMONG THE PARTIES
      HERETO.

     

    Section
      4.13  Joint
      and Several Liability.
      Each
      maker, signer, surety and endorser hereof, including without limitation each
      Borrower, as well as all heirs, successors and legal representatives of said
      parties, shall be directly and primarily, jointly and severally, liable for
      the
      payment of all indebtedness hereunder. Lender may release or modify the
      obligations of any of the foregoing persons or entities, or guarantors hereof,
      in connection with this loan without affecting the obligations of the others.
      

     

    Section
      4.14  Use
      of
      Funds.
      Borrower hereby warrants, represents and covenants that (i) the loan evidenced
      by this Note is made to Borrower solely for the purpose of acquiring or carrying
      on a business or commercial enterprise, (ii) all proceeds of this Note shall
      be
      used only for business and commercial purposes, and (iii) no funds disbursed
      hereunder shall be used for personal, family, agricultural or household
      purposes.

     

    Section
      4.15  Relationship
      of the Parties.
      Notwithstanding any prior business or personal relationship between Borrower
      and
      Lender, or any officer, director or employee of Lender, that may exist or have
      existed, the relationship between Borrower and Lender is solely that of debtor
      and creditor, Lender has no fiduciary or other special relationship with
      Borrower, Borrower and Lender are not partners or joint venturers, and no term
      or condition of any of the Loan Documents shall be construed so as to deem
      the
      relationship between Borrower and Lender to be
      other
      than that of debtor and creditor.

     

    Section
      4.16  Amendment
      and Restatement.
      THIS
      NOTE
      AMENDS, RESTATES AND MODIFIES THAT CERTAIN REVOLVING PROMISSORY NOTE, DATED
      JUNE
      29, 2006, EXECUTED BY BORROWER PAYABLE TO THE ORDER OF LENDER IN THE PRINCIPAL
      AMOUNT OF $2,000,000.00 (THE “ORIGINAL
      NOTE”).
      THIS
      NOTE IS GIVEN IN AMENDMENT, RESTATEMENT, REPLACEMENT, MODIFICATION AND
      SUBSTITUTION OF THE ORIGINAL NOTE AND SHALL NOT EXTINGUISH THE INDEBTEDNESS
      EVIDENCED BY THE ORIGINAL NOTE, AND THE OBLIGATIONS THEREOF AND HEREOF SHALL
      BE
      PAID IN ACCORDANCE WITH THE TERMS AND CONDITIONS HEREIN.

     

    [Remainder
      of page intentionally left blank]

    


     

    


     


    IN
      WITNESS WHEREOF, Borrower, intending to be legally bound hereby, has duly
      executed this Note as of the day and year first written above.

     

    BORROWER:

    


    LIGHTING
      SCIENCE GROUP CORPORATION,

    a
      Delaware corporation

    


    


    By:
              

    Name:      

    Title: