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| 1.01 | This      Agreement shall replace the following provisions of the ATTRLA and CRLA      addressed to royalty payments which would have been due under those      agreements and related matters: [ * ] of the ATTRLA and      [ * ] of the      CRLA.  Where other sections in these agreements refer to these      deleted sections the reference shall be deemed to be to the corresponding      Section of this SupplementalAgreement. |
|------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 1.02 | This      Agreement additionally includes future commitments for purchases of      Symyx’s Discovery Tools Systems and/or research services by TDCC and/or      its Affiliates.  This Agreement also contains a new structure      for directed research services to be performed by Symyx at the request of      TDCC. |
|------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| 1.03 | Except      as provided herein, the terms and conditions of the CRLA and ATTRLA shall      continue in full force and effect.  This Supplemental Agreement      shall be considered as an amendment to each of those      Agreements. |
|------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 2.01 | “Affiliate”shall have the      meaning as set out in the ATTRLA when it is used in this Agreement in      regard to rights or obligations related to Products arising from      technology licensed to TDCC under the ATTRLA or as set out in the CRLA      when it is used in this Agreement in regard to rights or obligations      related to Products arising from technology licensed to TDCC under the      CRLA.  Otherwise, Affiliate shall have the meaning given it in      the ATTRLA if the right or obligation addressed in this Agreement arises      in the ATTRLA, and Affiliate shall have the meaning given it in the CRLA      if the right or obligation addressed in this Agreement arises in the      CRLA. |
|------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 2.02 | “Agreement Compound”      means compounds which meet the definition of Agreement Compound under the      definition found in either the ATTRLA or the  CRLA. |
|------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 2.03 | [ *  ]. |
|------|---------|

| 2.04 | [ *  ]. |
|------|---------|

| 2.05 | [ *  ]. |
|------|---------|

| 2.06 | “Effective Date of this      Supplemental Agreement” means October 1, 2007, with the proviso      that with regard to [ *      ] this Supplemental Agreement shall become effective [ *  ]. |
|------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 2.07 | [ *  ]. |
|------|---------|

| 2.08 | [ *  ]. |
|------|---------|

| 2.09 | [ *  ]. |
|------|---------|

| 2.10 | [ *  ]. |
|------|---------|

| 2.11 | [ *  ]. |
|------|---------|

| 2.12 | [ *  ]. |
|------|---------|

| 2.13 | [ *  ]. |
|------|---------|

| 2.14 | [ *  ]. |
|------|---------|

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| 2.15 | [ * ]. |
|------|--------|

| 2.16 | [ * ]. |
|------|--------|

| 2.17 | [ * ]. |
|------|--------|

| 2.18 | “Product” has the      meaning as set forth in the ATTRLA and/orCRLA. |
|------|-----------------------------------------------------------------------------------|

| 2.19 | “Product Family” means      the various grades and generations of a Product that are based on common      manufacturing methods and common raw materials /or      components.   Examples of Products within a Product Family      include but are not limited to: |
|------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | a) | [ * ]. |
|--------|----|--------|

|   | b) | [ * ]. |
|--------|----|--------|

|   | c) | [ * ]. |
|--------|----|--------|

| 2.20 | [ * ]. |
|------|--------|

| 2.21 | [ * ]. |
|------|--------|

| 2.22 | “Royalty Term” has the      meaning as set forth in Article 4. |
|------|----------------------------------------------------------------------------|

| 2.23 | [ * ]. |
|------|--------|

| 3.01 | General      Principles |
|------|-------------------------|

|   | (a) | Except      as agreed herein by the Parties to the contrary, TDCC shall pay to Symyx      (a) a royalty on sales of Products by TDCC and its Affiliates and,      depending upon the election made by TDCC pursuant to Section 3.05(e), for      sales made by TDCC Joint Ventures, and (b) a share of payments from      Sublicensees for manufacture of Products as set forth    herein. |
|--------|-----|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|  | (b) | Royalties      will be determined by[ *  ] |
|--|-----|--------------------------------------------|

|   | (c) | [ * ]. |
|--------|-----|--------|

|   | (d) | [ * ]. |
|--------|-----|--------|

|   | (e) | [ * ]. |
|--------|-----|--------|

|   | (i) | [ *  ] |
|--------|-----|--------|

| 3.02 | [ *      ] Products.  New and      Existing. |
|------|--------------------------------------------------------|

|   | (a) | [ * ]. |
|--------|-----|--------|

|   | (b) | [ * ]. |
|--------|-----|--------|

|   | (c) | [ * ]. |
|--------|-----|--------|

|   | (d) | [ * ]. |
|--------|-----|--------|

----

|   | (e) | [ *  ]. |
|--------|-----|---------|

| 3.03 | [ *      ] Product from New [ * ] Product.   [ *      ]. |
|------|-------------------------------------------------------------------------|

| 3.04 | Other      Product. |
|------|---------------------|

|   | (a) | [ *  ]. |
|--------|-----|---------|

|   | (b) | [ *  ]. |
|--------|-----|---------|

| 3.05 | Sublicensing      income. |
|------|---------------------------|

|   | (d) | [ *  ]. |
|--------|-----|---------|

|   | (e) | [ *  ]. |
|--------|-----|---------|

|   | (f) | [ *  ]. |
|--------|-----|---------|

|   | (g) | [ *  ]. |
|--------|-----|---------|

|   | (h) | [ *  ]. |
|--------|-----|---------|

|   | (i) | [ *  ]. |
|--------|-----|---------|

| 4.01 | Royalties      on each Product Family shall be due for a period of [ * ] years from the      Commercialization Point for such Product      Family.  Notwithstanding the preceding, all royalty obligations      of TDCC and/or its Affiliates for Products  shall cease [ * ] years from the      Effective Date of this Supplemental Agreement. Provisions in the CRLA, the      ATTLRA and this Agreement related to royalties shall survive termination      of those agreements as required for purposes of this      Agreement. |
|------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 5.01 | TDCC      and Symyx agree that minimum royalties are due according to the following      schedule: |
|------|----------------------------------------------------------------------------------------------------|

|                      | [ * ]      | [ * ]      | [ * ]      | [ * ]      | [ * ]      | [ * ]      | [ * ]      | [ * ]      |
|---------------------------|------------|------------|------------|------------|------------|------------|------------|------------|
| Minimum Royalty[ * ] | [      * ] | [      * ] | [      * ] | [      * ] | [      * ] | [      * ] | [      * ] | [      * ] |

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| 6.01 | TDCC      shall notify Symyx promptly in writing after the Commercialization Point      for any given Product Family for which royalties are calculable has been      reached. TDCC shall make an annual written report to Symyx within [ * ] after the end of      each calendar year in which commercial sales of Products on which      royalties are payable occur.  The report shall include a      calculation of the royalties due, including the following for each Product      Family for which royalties are due, with the information stated separately      for TDCC and for each Affiliate: |
|------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | (a) | identity      of Product Family and value of Royalty Tracking Metric for Product in      Product Family sold ; |
|--------|-----|----------------------------------------------------------------------------------------------------------------|

|   | (b) | PVF      and Multiplier Factor for the Product Family and calculated royalty      due; |
|--------|-----|----------------------------------------------------------------------------------------|

|   | (c) | Any      withholding taxes held out pursuant to Section  6.05; |
|--------|-----|----------------------------------------------------------------|

|   | (d) | Any      credit for previously paid minimum royalties that are in excess of actual      royalties payable to date; |
|--------|-----|--------------------------------------------------------------------------------------------------------------------|

|   | (e) | Any      royalty due on sublicensing income pursuant to section    3.05; |
|--------|-----|--------------------------------------------------------------------------|

|   | (f) | If      payments for the year are less than the minimum royalty set out in Article      5 for that year, a statement of the amount of minimum royalty for the year      available as a credit against future actual royalties;  and |
|--------|-----|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|   | (g) | Actual      payment being made pursuant to the process in Section  6.02. |
|--------|-----|--------------------------------------------------------------------------|

| 6.02 | TDCC      shall make the minimum annual royalty payments identified in Section 5.01      in four equal installments, on a quarterly basis, within forty-five (45)      days after the end of each quarter. In addition, in accordance with the      terms of Section 5.01, the payment attributable to the fourth quarter of      each year shall include the excess of the royalties determined in      accordance with Article 3 (on an inception-to-date basis) over the minimum      royalties paid in accordance with Article 4 (on an inception-to-date      basis), if any. Royalty payments shall be wired by TDCC to the following      address : |
|------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| 6.03 | TDCC      and its Affiliates shall keep complete, true and accurate books of account      and records at a principal place of business for the purpose of      determining the royalty amounts (and revenues from sublicensing income)      which are payable by the party under this Agreement.  Such books      and records shall be kept for three years following the end of the      calendar year to which they pertain.  Such records will be made      available not more than once each calendar year at reasonable times and on      reasonable notice to a public accounting firm selected by Symyx and to      which TDCC has no reasonable objection.  Symyx shall bear the      cost of such inspection unless the inspection determines there was a      shortfall in payment in excess of the greater of [ * ] of amount stated      for the period covered by the inspection in which case reasonable costs of      such inspection will be paid by TDCC.  In addition, in the event      such shortfall is determined, TDCC will pay the amount of the shortfall      [ *      ].  The public accounting firm employees shall sign a      reasonable confidentiality agreement as a condition precedent to their      inspection and shall report to the party initiating the audit only that      information which would be contained in a royalty report prepared in      accordance with Section 6.01. |
|------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 6.04 | [ *  ] |
|------|--------|

| 6.05 | Taxes.  All      royalty amounts and other payments required to be paid hereunder may be      paid with deduction for withholding for or on account of any taxes (other      than taxes imposed on or measured by net income) or similar governmental      charge imposed by applicable law (“Withholding Taxes”).  Any      Withholding Taxes will be paid to the proper tax authorities and receipts      for such payment or other proof of payment will be made available by the      paying party to the other party.  The parties will exercise      diligent efforts to ensure that any withholding taxes imposed are reduced      as far as possible under provisions of any applicable      treaties.  TDCC may at its option have the relevant Dow      Affiliate directly make reports or payments to  Symyx. |
|------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 6.06 | Royalties      earned in local currency may be subject to foreign exchange regulations      then prevailing.  Royalty payments to Symyx shall be made in      United States dollars to the extent that free conversion to United States      dollars is permitted.  Any such conversion to U.S. dollars from      the currency in the country where such Net Royalty Income was earned shall      be made using the exchange rate for conversion of the foreign currency      into U.S. Dollars employed by TDCC in the normal course of its business      for other commercial transactions on the last business day of the calendar      year quarter to which such payment pertains.  If, due to      restrictions or prohibitions imposed by national or international      authority, payments cannot be made as aforesaid, the parties shall consult      with a view to finding a prompt and acceptable solution.  If      such royalties due Symyx in any country cannot be remitted to Symyx within      six (6) months after the end of the calendar year quarter during which      they are earned, then TDCC or its Affiliate shall upon request of Symyx      deposit the full amount of such unpaid royalties in a bank account in such      country in the name of Symyx, provided that if, due to restrictions or      prohibitions imposed by national or international authority, TDCC has not      received payment for the Products generating the royalty payment      obligation, the parties shall consult with a view to finding a timely and      acceptable solution. |
|------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| 7.01 | In      addition to commitments set out in the ATTRLA relating to future purchases      of Discovery Tools Systems or services provided under the Research      Program, TDCC hereby commits to additional purchases of Discovery Tools      Systems and/or research services from Symyx under Sections 7.01 and 7.02      of this Agreement according to the following  Table: |
|------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|                                                                                 | [ * ]      | [ * ]      | [ * ]      | [ * ]      | [ * ]      | [ * ]      |
|--------------------------------------------------------------------------------------|------------|------------|------------|------------|------------|------------|
| Purchases      of Discovery Tools Systems      or  research services ($MM) | [      * ] | [      * ] | [      * ] | [      * ] | [      * ] | [      * ] |

| 7.02 | Beginning      [ * ], TDCC may      elect to have Symyx perform directed research services. The parties shall      negotiate the terms of such arrangements, including but not limited to the      field in which TDCC would be free to use the results [ * ], with the      understanding that Symyx retain ownership of results related to      Combinatorial Chemistry and associated software, workflow and tools as      consistent with the principles set out in the ATTRLA. .  Symyx      will respond to directed research proposals with pricing options which are      expected in most instances to be between [ * ] depending on the      project being considered. |
|------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| 8.01 | The      parties shall negotiate in good faith to resolve issues arising under the      terms of this Agreement.  If the parties are unable to resolve      the issues themselves, the party raising the issue may submit the matter      to, binding arbitration as set out in Section 16.18 of the ATTRLA except      that the arbitration shall be conducted by one neutral arbitrator with      expertise in the chemical industry which both TDCC and Symyx approve and      the arbitration should be determined using the principles set out      herein. |
|------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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| 9.01 | This      Supplemental Agreement amends the ATTRLA and CRLA as stated      herein.  The other terms and conditions of the ATTRLA and CRLA      not explicitly replaced herein shall remain in full force and effect,      including confidentiality obligations, provisions regarding term and      termination, and the like. |
|------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| THE      DOW CHEMICAL COMPANY |                  | SYMYX      TECHNOLOGIES INC. |
|-------------------------------|-----------------------|------------------------------|
|                          |                  |                         |   |   |
| By:                           | /s/ Andrew N. Liveris |                         | By: | /s/ Rex S. Jackson |
|                          |                  |                         |   |   |
| Name:                         | Andrew N. Liveris     |                         | Name: | Rex S. Jackson |
|                          |                  |                         |   |   |
| Title:                        | Chairman & CEO    |                         | Title: | EVP & CFO |
|                          |                  |                         |   |   |
| Date:                         | 11/20/2007            |                         | Date: | 11/29/07 |

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