AMENDED AND RESTATED COMPANY GUARANTY AGREEMENT

AMENDED AND RESTATED COMPANY GUARANTY AGREEMENT dated as of September 22, 2001,
between MEMC ELECTRONIC MATERIALS, INC., a Delaware corporation ("MEMC" or the
"Guarantor"), and E.ON INTERNATIONAL FINANCE B.V., a company organized under the
laws of the Netherlands ("Finance"), as Agent and as Initial Lender (as defined
in the Credit Agreement referred to below).

Reference is made to the Amended and Restated Credit Agreement dated as of
September 22, 2001 (the "Credit Agreement"), between MEMC ELECTRONIC MATERIALS,
S.P.A., as Borrower, and Finance, as Initial Lender and as Agent. Capitalized
terms used herein and not defined herein shall have the meanings assigned to
such terms in the Credit Agreement.

The Lenders have agreed to make Advances to the Borrower, pursuant to, and upon
the terms and subject to the conditions specified in the Credit Agreement. The
Borrower is a wholly owned Subsidiary of MEMC, and MEMC acknowledges that it
will derive substantial benefit from the making of the Advances by the Lenders
to the Borrower. The obligations of the Lenders to make Advances to the Borrower
are conditioned on, among other things, the execution and delivery by MEMC of a
Guaranty Agreement in the form hereof. As consideration therefor and in order to
induce the Lenders to make Advances to the Borrower, MEMC is willing to execute
this Agreement.

Accordingly, the parties hereto agree as follows:

Amendment
. The Company Guaranty Agreement dated as of September 22, 2000 between MEMC and
Finance is amended and restated in its entirety as set forth in this Agreement.
Definitions
. As used in this Agreement, the following terms shall have the following
meanings (such meanings to be equally applicable to both the singular and plural
forms of the terms defined):

"Affiliate" means, as to any Person, any other Person that, directly or
indirectly, controls, is controlled by or is under common control with such
Person or is a director or officer of such Person. For purposes of this
definition, the term "control" (including the terms "controlling", "controlled
by" and "under common control with") of a Person means the possession, direct or
indirect, of the power to vote 50% or more of the voting stock of such Person or
to direct or cause the direction of the management and policies of such Person,
whether through the ownership of voting stock, by contract or otherwise.

"Approved Capital Expenditures" means the aggregate amount for Guarantor and its
Subsidiaries of (a) all purchases or acquisitions by Guarantor and its
Subsidiaries of items considered to be capital items under GAAP, which in any
event shall include all expenditures capitalized in accordance with GAAP
relating to property, plant, equipment or software on the consolidated balance
sheet of Guarantor and its Subsidiaries, and which shall exclude any such
purchases or acquisitions by a Subsidiary that were purchased or acquired with
Restricted Proceeds and/or with Restricted Net Free Cash Flow, plus (b) any
capital contributions or equity investments by Guarantor or its Subsidiaries in
Guarantor's unconsolidated joint ventures; provided, that such expenditures,
acquisitions, contributions or investments were contained in the annual budget
approved of in advance by the board of directors of Guarantor or were
subsequently approved by the board of directors of Guarantor. For purposes of
determining Approved Capital Expenditures for a Subsidiary in a particular year,
all Approved Capital Expenditures in such year shall only be considered to have
been purchased or acquired by such Subsidiary with Restricted Proceeds and/or
with Restricted Net Free Cash Flow to the extent that the Consolidated Net Free
Cash Flow as determined for such Subsidiary on a stand-alone basis (i.e., for
that Subsidiary and its consolidated Subsidiaries only) for that particular year
is equal to or less than the amount of the Approved Capital Expenditures by such
Subsidiary during such year.

"Change of Control" means the Initial Lender or any Affiliate of the Initial
Lender, through any transaction or series of transactions or otherwise, no
longer has beneficial ownership, directly or indirectly, of more than 50% of the
shares of common stock of the Borrower.

"Change of Control Date" means the date of occurrence of a Change of Control.

"Commitment" has the meaning specified in Section 2.01 of the Credit Agreement.

"Consolidated" refers to the consolidation of accounts in accordance with GAAP.

"Consolidated Net Free Cash Flow" shall mean, for any fiscal year, the following
amount:

(a)

the sum of:

(i)

Consolidated Net Income for such period, plus

(ii)

Consolidated Working Capital Adjustment, plus

(iii)

Consolidated depreciation and amortization expense during such period, plus

(iv)

the amount of cash dividends and distributions paid to Guarantor by Guarantor's
unconsolidated joint ventures during such period, plus

(v)

the excess, if any, of (i) the amount of expense for contributions to be made to
the MEMC Pension Plan and Guarantor's other retirement plans included in
Consolidated Net Income, over (ii) the amount of cash contributions made to the
MEMC Pension Plan and Guarantor's other retirement plans, plus

(vi)

any non-cash losses during such period not included in the foregoing items
(ii) through (v),

minus

(b)

the sum of:

(i)

the amount of Approved Capital Expenditures during such period, plus

(ii)

the aggregate amount of scheduled or required permanent principal payments of
Debt for borrowed money of Guarantor and its Subsidiaries during such period,
plus

(iii)

the aggregate amount of any voluntary permanent repayments of principal by
Guarantor on E.ON Loans (which repayments, in the case of any E.ON Loan that is
a revolving loan, are accompanied by a concurrent permanent reduction of the
revolving loan commitment) during such period, plus

(iv)

the excess, if any, of (i) the amount of cash contributions made to the MEMC
Pension Plan and Guarantor's other retirement plans, but only to the extent such
contributions are required pursuant to such plans or to meet minimum funding
standards or to avoid participant notice requirements of ERISA, over (ii) the
amount of expense for contributions to be made to the MEMC Pension Plan and
Guarantor's other retirement plans included in Consolidated Net Income, plus

(v)

any non-cash income during such period not included in items (i) through (iv).

Notwithstanding the foregoing, Consolidated Net Free Cash Flow shall exclude any
Restricted Net Free Cash Flow.

"Consolidated Net Income" means, for any period, the Consolidated net income (or
loss) of Guarantor and its Subsidiaries for such period (on a Consolidated basis
in conformity with GAAP).

"Consolidated Working Capital" means, as at any date of determination, the
excess (or deficit) of (a) the total assets of Guarantor and its Subsidiaries on
a Consolidated basis which may properly be classified as current assets in
conformity with GAAP, excluding the current portion of deferred tax assets and
cash and cash equivalents over (b) the total liabilities of Guarantor and its
Subsidiaries on a Consolidated basis which may properly be classified as current
liabilities in conformity with GAAP, excluding the current portions of Debt.

"Consolidated Working Capital Adjustment" means, for any period on a
Consolidated basis, the amount (which may be a negative number) by which
Consolidated Working Capital as of the beginning of such period exceeds (or is
less than) Consolidated Working Capital as of the end of such period.

"Debt" means (a) indebtedness for borrowed money, (b) obligations evidenced by
bonds, debentures, notes or other similar instruments, (c) obligations to pay
the deferred purchase price of property or services, (d) obligations as lessee
under leases which shall have been or should be, in accordance with generally
accepted accounting principles, recorded as capital leases, and (e) obligations
under direct or indirect guaranties (other than guaranties of Debt of MEMC's
Affiliates which Debt is otherwise included in Debt) in respect of, and
obligations (contingent or otherwise) to purchase or otherwise acquire, or
otherwise to assure a creditor against loss in respect of, indebtedness or
obligations of others of the kinds referred to in clause (a) through (d) of this
definition.

"Default" means any Event of Default or any event that would constitute an Event
of Default but for the requirement that notice be given or time elapse or both.

"Effective Date" has the meaning specified in Section 3.01 of the Credit
Agreement.

"E.ON Loans" mean any and all existing and future Debt of Guarantor to E.ON AG
and its Affiliates, including without limitation the term loans and revolving
loans outstanding between Guarantor and E.ON AG and its Affiliates on the date
hereof.

"ERISA" means the Employee Retirement Income Security Act of 1974, as amended
from time to time, and the regulations promulgated and rulings issued
thereunder.

"Events of Default" has the meaning specified in Section 6.01 of the Credit
Agreement.

"GAAP" means generally accepted accounting principles consistent with those
applied in the preparation of the financial statements referred to in
Section 10(e) and Section 11(a)(iv).

"Governmental Authority" means any nation or government, any state or other
political subdivision thereof, and any federal, state, local or foreign court or
governmental, executive, legislative, judicial, administrative or regulatory
agency, department, authority, instrumentality, commission, board or similar
body.

"Lender" means the Initial Lender and each Person that shall become a party to
the Credit Agreement pursuant to Section 8.07 of the Credit Agreement.

"Material Adverse Change" means any material adverse change in the business,
condition (financial or otherwise), operations, performance, properties or
prospects of MEMC and its Subsidiaries taken as a whole.

"MKC" means MEMC Korea Company, a corporation organized and existing under the
laws of the Republic of Korea formerly known as Posco Hüls Co., Ltd.

"Net Proceeds" means, with respect to any issuance of debt securities (including
debt securities convertible into equity) or any incurrence of Debt (other than
non-interest bearing Debt not for borrowed money (i.e., customer deposits),
other than Debt from E.ON AG or its Affiliates and other than Debt to the extent
incurred to refinance, in whole or in part, Debt for borrowed money outstanding
as of December 31, 2000), an amount equal to the cash proceeds received in
respect thereof (including cash proceeds received as income or other proceeds of
any noncash proceeds), less any direct expenses reasonably incurred by MEMC and
its Subsidiaries in connection therewith and excluding any Restricted Proceeds.

"Note" has the meaning specified in Section 3.

"Obligations" has the meaning specified in Section 3.

"Other Taxes" has the meaning specified in Section 8(c).

"Restricted Net Free Cash Flow" means Consolidated Net Free Cash Flow as
determined for a Subsidiary on a stand-alone basis (i.e., for that Subsidiary
and its consolidated Subsidiaries only), to the extent that the declaration or
payment of dividends or similar distributions by that Subsidiary of such net
free cash flow is not at that time permitted by operation of the terms of its
charter or any agreement, instrument, judgment, decree, order, statute, rule or
governmental regulation applicable to that Subsidiary.

"Restricted Proceeds" means cash proceeds received by a Subsidiary from any
issuance of debt securities or any incurrence of Debt, to the extent that the
declaration or payment of dividends or similar distributions by that Subsidiary
of such proceeds is not at that time permitted by operation of the terms of its
charter or any agreement, instrument, judgment, decree, order, statute, rule or
governmental regulation applicable to that Subsidiary.

"S&P" means Standard & Poor's Ratings Group, a division of McGraw Hill, Inc.

"Subsidiary" of any Person means any corporation, partnership, joint venture,
limited liability company, trust or estate of which (or in which) more than 50%
of (a) the issued and outstanding capital stock having ordinary voting power to
elect a majority of the board of directors of such corporation (irrespective of
whether at the time capital stock of any other class or classes of such
corporation shall or might have voting power upon the occurrence of any
contingency), (b) the interest in the capital or profits of such limited
liability company, partnership or joint venture or (c) the beneficial interest
in such trust or estate is at the time directly or indirectly owned or
controlled by such Person, by such Person and one or more of its other
Subsidiaries or by one or more of such Person's other Subsidiaries; provided,
however, that the term "Subsidiary" shall not include any joint venture of MEMC
with respect to any action or decision of the board of directors of such joint
venture if, by written agreement, such action or decision requires a vote in
excess of the number of members of such board of directors elected or controlled
by MEMC.

"Taxes" has the meaning specified in Section 8(b).

     Guaranty
     . The Guarantor unconditionally guaranties, as a primary obligor and not
     merely as a surety, (a) the due and punctual payment of (i) the principal
     of and premium, if any, and interest (including interest accruing during
     the pendency of any bankruptcy, insolvency, receivership or other similar
     proceeding, regardless of whether allowed or allowable in such proceeding)
     on the Advances, when and as due, whether at maturity, by acceleration,
     upon one or more dates set for prepayment or otherwise, (ii) each payment
     required to be made by any Borrower under the Credit Agreement or any note
     issued pursuant to the Credit Agreement (individually a "
     Note
     " and collectively the "
     Notes
     "), when and as due, including payments in respect of reimbursement of
     disbursements, interest thereon and obligations to provide cash collateral
     and (iii) all other monetary obligations, including fees, costs, expenses
     and indemnities, whether primary, secondary, direct, contingent, fixed or
     otherwise (including monetary obligations incurred during the pendency of
     any bankruptcy, insolvency, receivership or other similar proceeding,
     regardless of whether allowed or allowable in such proceeding), of the
     Borrower under the Credit Agreement or any Note, and (b) the due and
     punctual performance of all covenants, agreements, obligations and
     liabilities of the Borrower under or pursuant to the Credit Agreement or
     any Note (all the monetary and other obligations referred to in the
     preceding clauses (a) through (b) being collectively called the "
     Obligations
     "). The Guarantor further agrees that the Obligations may be extended or
     renewed, in whole or in part, without notice to or further assent from it,
     and that it will remain bound upon its guaranty notwithstanding any
     extension or renewal of any Obligation.
     Obligations Not Waived
     . To the fullest extent permitted by applicable law, the Guarantor waives
     presentment to, demand of payment from and protest to the Borrower of any
     of the Obligations, and also waives notice of acceptance of its guaranty
     and notice of protest for nonpayment. To the fullest extent permitted by
     applicable law, the obligations of the Guarantor hereunder shall not be
     affected by (a) the failure of the Agent or any Lender to assert any claim
     or demand or to enforce or exercise any right or remedy against any
     Borrower or any guarantor under the provisions of the Credit Agreement, any
     Note, any guaranty agreement, or otherwise, or (b) any rescission, waiver,
     amendment or modification of, or any release from any of the terms or
     provisions of this Guaranty Agreement, the Credit Agreement, any Note, any
     guaranty agreement, or any other agreement.
     Guaranty of Payment
     . The Guarantor further agrees that its guaranty constitutes a guaranty of
     payment when due and not of collection, and waives any right to require
     that any resort be had by the Agent or any Lender to the Borrower or to any
     other guarantor or to any of the security held for payment of the
     Obligations or to any balance of any deposit account or credit on the books
     of the Agent or any other Lender in favor of any Borrower or any other
     person.
     No Discharge or Diminishment of Guaranty.
     The obligations of the Guarantor hereunder shall not be subject to any
     reduction, limitation, impairment or termination for any reason (other than
     the indefeasible payment in full in cash of the Obligations), including any
     claim of waiver, release, surrender, alteration or compromise of any of the
     Obligations, and shall not be subject to any defense or setoff,
     counterclaim, recoupment or termination whatsoever by reason of the
     invalidity, illegality or unenforceability of the Obligations or otherwise.
     Without limiting the generality of the foregoing, the obligations of the
     Guarantor hereunder shall not be discharged or impaired or otherwise
     affected by the failure of the Agent or any Lender or any other party to
     assert any claim or demand or to enforce any remedy under the Credit
     Agreement or any other agreement, by any waiver or modification of any
     provision of any thereof, by any default, failure or delay, willful or
     otherwise, in the performance of the Obligations, or by any other act or
     omission that may or might in any manner or to any extent vary the risk of
     the Guarantor or that would otherwise operate as a discharge of the
     Guarantor as a matter of law or equity (other than the indefeasible payment
     in full in cash of all the Obligations).
 1.   Defenses of Borrower Waived. To the fullest extent permitted by applicable
     law, the Guarantor waives any defense based on or arising out of any
     defense of the Borrower or the unenforceability of the Obligations or any
     part thereof from any cause, or the cessation from any cause of the
     liability of the Borrower, other than the final payment in full in cash of
     the Obligations. The Agent may, at its election, foreclose on any security
     held by judicial or nonjudicial sale, accept an assignment of any such
     security in lieu of foreclosure, compromise or adjust any part of the
     Obligations, make any other accommodation with the Borrower or any other
     guarantor or exercise any other right or remedy available to it against the
     Borrower, or any other guarantor, without affecting or impairing in any way
     the liability of the Guarantor hereunder except to the extent the
     Obligations have been fully and finally paid in cash or otherwise satisfied
     pursuant to the terms of the Credit Agreement. Pursuant to applicable law,
     the Guarantor waives any defense arising out of any such election even
     though such election operates, pursuant to applicable law, to impair or to
     extinguish any right of reimbursement or other right or remedy of the
     Guarantor against the Borrower or any other guarantor, as the case may be,
     or any security.
 2.   Agreement to Pay; Subordination. (a) In furtherance of the foregoing and
     not in limitation of any other right that the Agent, any Lender or any
     other party has at law or in equity against the Guarantor by virtue hereof,
     upon the failure of the Borrower to pay any Obligation when and as the same
     shall become due, whether at maturity, by acceleration, after notice of
     prepayment or otherwise, the Guarantor hereby promises to and will
     forthwith pay, or cause to be paid, to the Agent as designated thereby in
     cash the amount of such unpaid Obligations. Upon payment by the Guarantor
     of any sums to the Agent as provided above, all rights of the Guarantor
     against the Borrower arising as a result thereof by way of right of
     subrogation, contribution, reimbursement, indemnity or otherwise shall in
     all respects be subordinate and junior in right of payment to the prior
     payment in full in cash of all the Obligations. In addition, any
     indebtedness of the Borrower now or hereafter held by the Guarantor is
     hereby subordinated in right of payment to the prior payment in full of the
     Obligations. If any amount shall erroneously be paid to the Guarantor on
     account of (i) such subrogation, contribution, reimbursement, indemnity or
     similar right or (ii) any such indebtedness of the Borrower, and if an
     Event of Default shall have occurred and be continuing, such amount shall
     be held in trust for the benefit of the Borrower and shall forthwith be
     paid to the Agent to be credited against the payment of the Obligations,
     whether matured or unmatured, in accordance with the terms of the Credit
     Agreement.

     (b)  Any and all payments by the Guarantor hereunder shall be made free and
     clear of and without deduction for any and all present or future taxes,
     levies, imposts, deductions, charges or withholdings, and all liabilities
     with respect thereto, excluding, in the case of each Lender and the Agent,
     net income taxes (or franchise taxes imposed in lieu thereof) that are
     imposed on such Lender or the Agent by the state or foreign jurisdiction
     under the laws of which such Lender or the Agent (as the case may be) is
     organized or any political subdivision thereof and, in the case of each
     Lender, net income taxes (or franchise taxes imposed in lieu thereof) that
     are imposed on such Lender by the state or foreign jurisdiction of such
     Lender's Domestic Lending Office or any political subdivision thereof (all
     such nonexcluded taxes, levies, imposts, deductions, charges, withholdings
     and liabilities in respect of payments hereunder being hereinafter referred
     to as "Taxes"). If the Guarantor shall be required by law to deduct any
     Taxes from or in respect of any sum payable hereunder or under any Note,
     (i) the sum payable shall be increased as may be necessary so that, after
     making all required deductions (including deductions applicable to
     additional sums payable under this Section 8), such Lender or the Agent
     receives an amount equal to the sum it would have received had no such
     deductions been made, (ii) the Guarantor shall make such deductions and
     (iii) the Guarantor shall pay the full amount deducted to the relevant
     taxation authority or other authority in accordance with applicable law.

     (c) In addition, the Guarantor shall pay any present or future stamp,
     documentary, excise, property or other taxes, charges or levies that arise
     from any payment made hereunder or from the execution, delivery or
     registration of, or otherwise with respect to, this Guaranty (hereinafter
     referred to as "Other Taxes").

     (d) The Guarantor shall indemnify each Lender and the Agent for the full
     amount of Taxes or Other Taxes and for the full amount of Taxes or Other
     Taxes imposed by any jurisdiction on amounts payable under this Section 8
     imposed on or paid by such Lender or the Agent (as the case may be) or any
     liability (including penalties, additions to tax, interest and expenses)
     arising therefrom or with respect thereto, whether or not such Taxes or
     Other Taxes were correctly or legally asserted. This indemnification shall
     be made within 30 days from the date such Lender or the Agent makes written
     demand therefor.

     (e) Within 30 days after the date of any payment of Taxes, the Guarantor
     shall furnish to the Agent, at its address referred to in Section 8.02 of
     the Credit Agreement, the original receipt of payment or a certified copy
     of such receipt. If no Taxes are payable in respect of any payment
     hereunder, the Guarantor shall furnish to the Agent, at such address, a
     certificate from each appropriate taxing authority, or an opinion of
     counsel acceptable to the Lenders, in either case stating that such payment
     is exempt from or not subject to Taxes.

     (f) Each Lender organized under the laws of a jurisdiction outside the
     United States shall, prior to payment of unpaid Obligations by the
     Guarantor pursuant to Section 8(a) and from time to time thereafter if
     requested in writing by the Guarantor or the Agent (but only so long as
     such Lender remains lawfully able to do so), provide each of the Guarantor
     and the Agent with Internal Revenue Service form W-8, W-BEN or W-8ECI, as
     appropriate, or any successor or other form prescribed by the Internal
     Revenue Service, certifying that such Lender is exempt from or entitled to
     a reduced rate of United States withholding tax on payments of interest
     pursuant to this Guaranty. If any form or document referred to in this
     subsection (f) requires the disclosure of information, other than
     information necessary to compute the tax payable and information required
     on the date hereof by Internal Revenue Service form W-8, W-BEN or W-8ECI,
     that the Lender reasonably considers to be confidential, the Lender shall
     give notice thereof to the Guarantor and shall not be obligated to include
     in such form or document such confidential information.

     (g) For any period with respect to which a Lender has failed to provide the
     Guarantor with the appropriate form described in Section 8(f) (other than
     if such failure is due to a change in law occurring subsequent to the date
     on which a form originally was required to be provided), such Lender shall
     not be entitled to indemnification under Section 8(b) with respect to Taxes
     imposed by the United States until such form is provided; provided,
     however, that should such Lender become subject to Taxes because of its
     failure to deliver a form required hereunder, the Guarantor shall take such
     steps as such Lender shall reasonably request to assist such Lender to
     recover such Taxes.

     (h) If following any amount paid under this Section 8, the Lender receives
     or is granted a credit against or remission for any Taxes or Other Taxes
     payable by such Lender which the Lender determines, in its sole and
     absolute discretion, is attributable to any Taxes or Other Taxes paid
     hereunder, such Lender shall, subject to the Guarantor having made any
     increased payment hereunder and to the extent such Lender can do so in its
     sole opinion without prejudicing the retention of the amount of such credit
     or remission and without prejudice to its rights to obtain any other relief
     or allowance which may be available to such Lender and to conduct its own
     tax affairs as it sees fit, reimburse such amount to the Guarantor as the
     Lender shall in its sole and absolute discretion certify to be the
     proportion of such credit or remission as will leave the Lender (after such
     reimbursement) in no worse position than it would have been in had no
     payment been required under this Section 8. Such reimbursement shall be
     made promptly upon the Lender certifying that the amount of such credit or
     remission has been received by it; provided, however, that no such payment
     shall be made so long as an Event of Default shall have occurred and be
     continuing. The disallowance or reduction of any credit or remission of
     Taxes or Other Taxes with respect to which a Lender has made a payment to
     Guarantor under this Section 8 shall be treated as Taxes for which
     Guarantor is obligated to indemnify such Lender hereunder. Notwithstanding
     the above, no Lender shall (i) be under any obligation to claim a tax
     credit in priority to any other claim, relief, credit or deduction
     available to such Lender or (ii) be obligated to disclose any information
     regarding its tax affairs or computations to the Guarantor.

 3.   Information. The Guarantor assumes all responsibility for being and
     keeping itself informed of the Borrower's financial condition and assets,
     and of all other circumstances bearing upon the risk of nonpayment of the
     Obligations and the nature, scope and extent of the risks that the
     Guarantor assumes and incurs hereunder, and agrees that none of the Agent
     or any other Lender will have any duty to advise the Guarantor of
     information known to it or any of them regarding such circumstances or
     risks.
 4.   Representations and Warranties. Effective as of the Effective Date, MEMC
     represents and warrants as follows:

     (a) MEMC is a corporation duly organized, validly existing and in good
     standing under the laws of the State of Delaware.

     (b) The execution, delivery and performance by MEMC of this Guaranty
     Agreement are within MEMC's corporate powers, have been duly authorized by
     all necessary corporate action, and do not contravene (i) MEMC's charter or
     by-laws or (ii) any law or any contractual restriction binding on or
     affecting MEMC.

     (c) No authorization or approval or other action by, and no notice to or
     filing with, any Governmental Authority is required for the due execution,
     delivery and performance by MEMC of this Guaranty Agreement.

     (d) This Guaranty Agreement has been duly executed and delivered by MEMC.
     This Guaranty Agreement is a legal, valid and binding obligation of MEMC
     enforceable against MEMC in accordance with its terms.

     (e) The Consolidated balance sheets of MEMC and its Subsidiaries as of
     December 31, 1999 and June 30, 2000, and the related Consolidated
     statements of income and cash flows of MEMC and its Subsidiaries for the
     fiscal year and the six months then ended, copies of which have been
     furnished to the Lenders, fairly present the financial condition of MEMC
     and its Subsidiaries as at such dates and the results of the operations of
     MEMC and its Subsidiaries for the periods ended on such dates, all in
     accordance with GAAP. Since June 30, 2000, there has been no Material
     Adverse Change.

     (f) There is no pending or threatened action or proceeding affecting MEMC
     or any of its Subsidiaries before any court, governmental agency or
     arbitrator, that (i) may materially adversely affect the financial
     condition or operations of MEMC or any of its Subsidiaries or (ii) purports
     to affect the legality, validity or enforceability of the Credit Agreement,
     this Guaranty Agreement or the consummation of the transactions
     contemplated hereby.

     (g) MEMC is not engaged in the business of extending credit for the purpose
     of purchasing or carrying margin stock (within the meaning of Regulation U
     issued by the Board of Governors of the Federal Reserve System), and no
     proceeds of any Advance will be used to purchase or carry any margin stock
     or to extend credit to others for the purpose of purchasing or carrying any
     margin stock.

     (h) The Obligations of MEMC under this Guaranty Agreement rank pari passu
     with all other unsecured obligations of MEMC that are not, by their terms,
     expressly subordinate to such other obligations of MEMC.

     (i) The representations and warranties of the Borrower set forth in the
     Credit Agreement are true and accurate.

     (j) No event has occurred or is continuing that constitutes a Default.

 5.   Covenants.  (a)  Affirmative Covenants. On and after the Change of Control
     Date and so long as any Advance shall remain unpaid or any Lender shall
     have any Commitment under the Credit Agreement, MEMC will, unless the
     Lenders shall otherwise consent in writing:

     (i) Compliance with Laws, Etc. Comply, and cause each of its Subsidiaries
     to comply, in all material respects, with all applicable laws, rules,
     regulations and orders, such compliance to include, without limitation,
     compliance with ERISA and environmental laws.

     (ii) Payment of Taxes, Etc. Pay and discharge, and cause each of its
     Subsidiaries to pay and discharge, before the same shall become delinquent,
     (i) all taxes, assessments and governmental charges or levies imposed upon
     it or upon its property and (ii) all lawful claims that, if unpaid, might
     by law become a lien upon its property; provided, however, that neither
     MEMC nor any of its Subsidiaries shall be required to pay or discharge any
     such tax, assessment, charge or claim that is being contested in good faith
     and by proper proceedings and as to which appropriate reserves are being
     maintained, unless and until any lien resulting therefrom attaches to its
     property and becomes enforceable against its other creditors.

     (iii) Preservation of Corporate Existence, Etc. Preserve and maintain, and
     cause each of its Subsidiaries to preserve and maintain, its corporate
     existence, rights (charter and statutory) and franchises; provided,
     however, that neither MEMC nor any of its Subsidiaries shall be required to
     preserve any right or franchise if the board of directors of MEMC or a
     Subsidiary shall determine that the preservation thereof is no longer
     desirable in the conduct of the business of MEMC or such Subsidiary, as the
     case may be, and that the loss thereof is not disadvantageous in any
     material respect to MEMC, the Subsidiary or the Lenders.

     (iv) Keeping of Books. Keep, and cause each of its Subsidiaries to keep,
     proper books of record and account, in which full and correct entries shall
     be made of all financial transactions and the assets and business of MEMC
     and each such Subsidiary in accordance with GAAP or, in the case of any
     Subsidiary organized under the laws of a jurisdiction other than the United
     States or any state thereof, the equivalent of GAAP applicable in such
     jurisdiction.

     (v) Maintenance of Properties, Etc. Maintain and preserve, and cause each
     of its Subsidiaries to maintain and preserve, all of its properties that
     are used or useful in the conduct of its business in good working order and
     condition, ordinary wear and tear excepted.

     (vi) Reporting Requirements. Furnish to the Lenders:

     (A) as soon as available and in any event within 45 days after the end of
     each of the first three quarters of each fiscal year of MEMC, Consolidated
     balance sheets of MEMC and its Subsidiaries as of the end of such quarter
     and Consolidated statements of income and cash flows of MEMC and its
     Subsidiaries for the period commencing at the end of the previous fiscal
     year and ending with the end of such quarter, duly certified (subject to
     year-end audit adjustments) by the chief financial officer of the Borrower
     as having been prepared in accordance with GAAP;

     (B) as soon as available and in any event within 90 days after the end of
     each fiscal year of the Borrower, a copy of the annual report for such year
     for the Borrower and its Subsidiaries, containing Consolidated balance
     sheets of the Borrower and its Subsidiaries as of the end of such fiscal
     year and Consolidated statements of income and cash flows of the Borrower
     and its Subsidiaries for such fiscal year, in each case accompanied by an
     opinion acceptable to the Lenders by KPMG Peat Marwick or other independent
     public accountants reasonably acceptable to the Lenders;

     (C) as soon as possible and in any event within ten days after the
     occurrence of each Default continuing on the date of such statement, a
     statement of the chief financial officer of MEMC setting forth details of
     such Default and the action that MEMC has taken and proposes to take with
     respect thereto;

     (D) promptly after the sending or filing thereof, copies of all reports
     which MEMC sends to any of its securityholders, and copies of all reports
     and registration statements which MEMC or any of its Subsidiaries files
     with the Securities and Exchange Commission or any national securities
     exchange;

     (E) promptly after the filing or receiving thereof, copies of all reports
     and notices which MEMC or any Subsidiary files under ERISA with the
     Internal Revenue Service or the Pension Benefit Guaranty Corporation or the
     U.S. Department of Labor or which MEMC or any Subsidiary receives from the
     Pension Benefit Guaranty Corporation;

     (F) promptly after the commencement thereof, notice of all actions and
     proceedings before any court, governmental agency or arbitrator affecting
     MEMC or any of its Subsidiaries of the type described in Section 10(f); and

     (G) such other information respecting MEMC or any of its Subsidiaries as
     any Lender through the Agent may from time to time reasonably request.

     (b) Negative Covenants. On and after the date hereof, and so long as any
     Advance shall remain unpaid or any Lender shall have any Commitment
     hereunder, MEMC will not, unless the Lenders shall otherwise consent in
     writing:

     (i) Liens, Etc. Create or suffer to exist, or permit any of its
     Subsidiaries to create or suffer to exist, any lien, security interest or
     other charge or encumbrance, or any other type of preferential arrangement,
     upon or with respect to any of its properties, whether now owned or
     hereafter acquired, or assign, or permit any of its Subsidiaries to assign,
     any right to receive income, in each case to secure any Debt of any Person,
     other than:

     (A) purchase money liens or purchase money security interests upon or in
     any property acquired or held by MEMC or any Subsidiary in the ordinary
     course of business to secure the purchase price of such property or to
     secure indebtedness incurred solely for the purpose of financing the
     acquisition of such property;

     (B) liens or security interests existing on such property at the time of
     its acquisition (other than any such lien or security interest created in
     contemplation of such acquisition);

     (C) liens for taxes, assessments and governmental charges or levies to the
     extent not required to be paid under Section 11(a)(ii) hereof;

     (D) liens imposed by law, such as materialmen's, mechanics', carriers',
     workmen's and repairmen's liens and other similar liens arising in the
     ordinary course of business securing obligations that are not overdue for a
     period of more than 30 days;

     (E) pledges or deposits to secure obligations under workers' compensation
     laws or similar legislation or to secure public or statutory obligations;

     (F) easements, rights of way and other encumbrances on title to real
     property that do not render title to the property encumbered thereby
     unmarketable or materially adversely affect the use of such property for
     its present purposes; and

     (G) liens incurred or deposits made in the ordinary course of business to
     secure the performance of letters of credit, bids, tenders, sales
     contracts, leases, surety, appeal and performance bonds and other similar
     obligations not incurred in connection with the borrowing of money;

     provided

     that the aggregate principal amount of the Debt, other indebtedness, taxes,
     assessments, governmental charges or levies and other obligations secured
     by the liens or security interests referred to in clauses (A) through (G)
     of this Section 11(b)(i) shall not exceed $45,000,000 in the aggregate at
     any time outstanding.

     

     (ii) Accounting Changes. Make or permit, or permit any of its Subsidiaries
     to make or permit, any change in accounting policies or reporting
     practices, except as allowed by generally accepted accounting principles.

     (c) Required Repayment under the Credit Agreement. On and after the
     Effective Date and so long as any Advance shall remain unpaid or any Lender
     shall have any Commitment under the Credit Agreement, MEMC will, unless the
     Lenders shall otherwise consent in writing:

     (i) Obtain Funds from MKC. Use reasonable commercial efforts, and cause the
     Borrower to use reasonable commercial efforts, to obtain cash from MKC by
     way of dividends or loans (taking into account tax consequences and MKC's
     reasonable capital requirements), which amounts shall then be payable to
     the Lenders as a mandatory repayment pursuant to Section 5.02 of the Credit
     Agreement.

     (ii) Mandatory Repayment of MKC Funds. Within ten (10) days after each date
     upon which MEMC or its Subsidiaries receives any cash from MKC from
     dividends, reductions or repurchases of equity, share redemptions or loans,
     cause the Borrower to pay the Lenders an amount equal to 75% of any such
     cash received from MKC less any applicable taxes as a mandatory repayment
     of the outstanding principal amount of the Advances, together with accrued
     interest to the date of such repayment on the principal amount repaid.

     (iii) Within ten (10) days after each date upon which MEMC or its
     Subsidiaries receives any Net Proceeds, cause the Borrower to pay to the
     Lenders an amount equal to 100% of the Net Proceeds as a mandatory
     repayment of the outstanding principal amount of the Advances, together
     with accrued interest to the date of such repayment on the principal amount
     repaid.

     (iv) Cause the Borrower to comply with its obligations under the Credit
     Agreement.

     (d) Mandatory Repayment and Other Covenants.

     (i) In addition to any other mandatory repayments or commitment reductions
     pursuant to this Agreement, within 90 days after the end of each fiscal
     year commencing with the fiscal year ending December 31, 2001, Guarantor
     shall pay E.ON AG an amount equal to 50% of the Consolidated Net Free Cash
     Flow for such year as a mandatory repayment of principal of outstanding
     E.ON Loans in accordance with the requirements of Section 11(d)(iii).
     Within 80 days after the end of each fiscal year, Guarantor shall deliver
     to E.ON AG a certificate setting forth its calculation of the Consolidated
     Net Free Cash Flow for the prior year and the components thereof, together
     with documents supporting such calculation.

     (ii) To the extent that any Subsidiary has Restricted Proceeds and/or
     Restricted Net Free Cash Flow in a fiscal year, Guarantor shall use
     reasonable commercial efforts to obtain as soon as practicable such
     Restricted Proceeds and/or Restricted Net Free Cash Flow from such
     Subsidiary by way of loans, dividends or similar distributions (taking into
     account tax consequences and such Subsidiary's reasonable capital
     requirements) in subsequent fiscal years and, in the case of Restricted
     Proceeds, in the same fiscal year. Any such Restricted Proceeds and/or
     Restricted Net Free Cash Flow received by Guarantor in subsequent fiscal
     years by way of loans, dividends, reductions or repurchases of equity,
     share redemptions or similar distributions shall be considered Net Proceeds
     or Consolidated Net Free Cash Flow, as the case may be, in such subsequent
     fiscal years, and within forty-five (45) days following the end of the
     calendar quarter in which such funds have been received by Guarantor,
     Guarantor shall pay to E.ON AG as a mandatory repayment of principal of
     outstanding E.ON Loans an amount equal to 50% of the Restricted Net Free
     Cash Flow so received by Guarantor and 75% of the Restricted Proceeds so
     received by Guarantor. For purposes of this Section 11(d)(ii), the amount
     of Restricted Net Free Cash Flow generated in a particular fiscal year
     shall be limited to the lesser of (i) the Restricted Net Free Cash Flow for
     such fiscal year and (ii) the sum of the Consolidated Net Free Cash Flow
     and the Restricted Net Free Cash Flow for such fiscal year. By way of
     illustration, if the Consolidated Net Free Cash Flow for a particular
     fiscal year is negative $10 million and the Restricted Net Free Cash Flow
     for such fiscal year is positive $30 million, then for purposes of this
     Section 11(d)(ii) the Restricted Net Free Cash Flow considered to be
     generated in such fiscal year shall be $20 million.

     (iii) Each amount required to be applied to repay E.ON Loans pursuant to
     Section 11(d)(i) or (ii) shall be applied (i) first, to repay the remaining
     scheduled principal payments of the then outstanding E.ON Loans that are
     term loans, and (ii) second, if all outstanding E.ON Loans that are term
     loans have been fully repaid, to repay the principal amount of any then
     outstanding E.ON Loans that are revolving loans (and permanently reduce the
     revolving loan commitment under such loan); provided, that in each case,
     Guarantor shall propose to E.ON AG, and Guarantor and E.ON AG shall seek to
     agree on, which term loan or revolving loan shall be repaid and which
     advance or advances thereunder; provided, further, that if Guarantor and
     E.ON AG cannot agree on which term loan or revolving loan and which
     advances shall be repaid, E.ON AG may make such determination in its sole
     discretion. In addition to each amount required to be applied to repay E.ON
     Loans pursuant to Section 11(d)(i) or (ii) Guarantor shall pay accrued
     interest to the date of such repayment on the principal amount repaid.

 6.   Termination. The Guaranty made hereunder (a) shall terminate when all the
     Obligations have been paid in full and the Lenders have no further
     commitment to lend to any Borrower under the Credit Agreement and (b) shall
     be reinstated if, at any time after the Guaranty has terminated, payment,
     or any part thereof, of any Obligation is rescinded or must otherwise be
     restored by the Guarantor or any other guarantor upon the bankruptcy or
     reorganization of any Borrower, MEMC, any other guarantor or otherwise.
 7.   Binding Effect; Several Agreement; Assignments. Whenever in this Agreement
     any of the parties hereto is referred to, such reference shall be deemed to
     include the successors and assigns of such party; and all covenants,
     promises and agreements by or on behalf of MEMC that are contained in this
     Agreement shall bind and inure to the benefit of each party hereto and
     their respective successors and assigns. This Agreement shall become
     effective as to MEMC when a counterpart hereof executed on behalf of MEMC
     shall have been delivered to the Agent, and a counterpart hereof shall have
     been executed on behalf of the Agent, and thereafter shall be binding upon
     MEMC and the Agent and their respective successors and assigns, and shall
     inure to the benefit of MEMC, the Agent and the Lenders, and their
     respective successors and assigns, except MEMC shall not have the right to
     assign its rights or obligations hereunder or any interest herein (and any
     such attempted assignment shall be void).
 8.   Waivers; Amendment.

     (a) No failure or delay of the Agent or any Lender in exercising any power
     or right hereunder shall operate as a waiver thereof, nor shall any single
     or partial exercise of any such right or power, or any abandonment or
     discontinuance of steps to enforce such a right or power, preclude any
     other or further exercise thereof or the exercise of any other right or
     power. The rights and remedies of the Agent and of the Lenders hereunder
     and under the Credit Agreement are cumulative and are not exclusive of any
     rights or remedies that they would otherwise have. No waiver of any
     provision of this Agreement or consent to any departure by MEMC therefrom
     shall in any event be effective unless the same shall be permitted by
     paragraph (b) below, and then such waiver or consent shall be effective
     only in the specific instance and for the purpose for which given. No
     notice or demand on MEMC in any case shall entitle MEMC to any other or
     further notice or demand in similar or other circumstances.

     (b) Neither this Agreement nor any provision hereof may be waived, amended
     or modified except pursuant to a written agreement entered into between
     MEMC and the Agent, with the prior written consent of the Lenders (except
     as otherwise provided in the Credit Agreement).

 9.   Governing Law. THIS AGREEMENT SHALL BE GOVERNED BY, AND CONSTRUED IN
     ACCORDANCE WITH, THE LAWS OF THE STATE OF NEW YORK.
 10.  Notices. All communications and notices hereunder shall be in writing and
     given as provided in Section 8.02 of the Credit Agreement, except the
     address for MEMC shall be 501 Pearl Drive, St. Peters, Missouri 63376,
     Attention: Treasurer (telecopier number (636) 474-5158).
 11.  Survival of Agreement; Severability.

     (a) All covenants, agreements, representations and warranties made by MEMC
     herein and in the certificates or other instruments prepared or delivered
     in connection with or pursuant to this Agreement or the Credit Agreement
     shall be considered to have been relied upon by the Agent and the other
     Parties and shall survive the making by the Lenders of the Advances to the
     Borrower, and shall continue in full force and effect as long as the
     principal of or any accrued interest on any Advance to the Borrower or any
     other fee or amount payable under this Agreement or the Credit Agreement by
     the Borrower is outstanding and unpaid.

     (b) In the event any one or more of the provisions contained in this
     Agreement or the Credit Agreement should be held invalid, illegal or
     unenforceable in any respect, the validity, legality and enforceability of
     the remaining provisions contained herein and therein shall not in any way
     be affected or impaired thereby (it being understood that the invalidity of
     a particular provision in a particular jurisdiction shall not in and of
     itself affect the validity of such provision in any other jurisdiction).
     The parties shall endeavor in good-faith negotiations to replace the
     invalid, illegal or unenforceable provisions with valid provisions the
     economic effect of which comes as close as possible to that of the invalid,
     illegal or unenforceable provisions.

 12.  Counterparts. This Agreement may be executed in counterparts, each of
     which shall constitute an original, but all of which when taken together
     shall constitute a single contract, and shall become effective as provided
     in Section 12. Delivery of an executed signature page to this Agreement by
     facsimile transmission shall be as effective as delivery of a manually
     executed counterpart of this Agreement.
 13.  Rules of Interpretation. The rules of interpretation specified in
     Section 1.1 of the Credit Agreement shall be applicable to this Agreement.
 14.  Jurisdiction; Consent to Service of Process.

     (a) MEMC hereby irrevocably and unconditionally submits, for itself and its
     property, to the nonexclusive jurisdiction of any New York State court or
     Federal court of the United States of America sitting in New York City, and
     any appellate court from any thereof, in any action or proceeding arising
     out of or relating to this Agreement or the Credit Agreement, or for
     recognition or enforcement of any judgment, and each of the parties hereto
     hereby irrevocably and unconditionally agrees that all claims in respect of
     any such action or proceeding may be heard and determined in such New York
     State or, to the extent permitted by law, in such Federal court. Each of
     the parties hereto agrees that a final judgment in any such action or
     proceeding shall be conclusive and may be enforced in other jurisdictions
     by suit on the judgment or in any other manner provided by law. Nothing in
     this Agreement shall affect any right that the Agent, any Lender or any
     other party may otherwise have to bring any action or proceeding relating
     to this Agreement or the Credit Agreement against MEMC or its properties in
     the courts of any jurisdiction.

     (b) The Guarantor hereby irrevocably and unconditionally waives, to the
     fullest extent it may legally and effectively do so, any objection that it
     may now or hereafter have to the laying of venue of any suit, action or
     proceeding arising out of or relating to this Agreement or the Credit
     Agreement in any New York State or Federal court. Each of the parties
     hereto hereby irrevocably waives, to the fullest extent permitted by law,
     the defense of an inconvenient forum to the maintenance of such action or
     proceeding in any such court.

     (c) Each party to this Agreement irrevocably consents to service of process
     in the manner provided for notices in Section 16. Nothing in this Agreement
     will affect the right of any party to this Agreement to serve process in
     any other manner permitted by law.

 15.  Waiver of Jury Trial. EACH PARTY HERETO HEREBY WAIVES, TO THE FULLEST
     EXTENT PERMITTED BY APPLICABLE LAW, ANY RIGHT IT MAY HAVE TO A TRIAL BY
     JURY IN RESPECT OF ANY LITIGATION DIRECTLY OR INDIRECTLY ARISING OUT OF,
     UNDER OR IN CONNECTION WITH THIS AGREEMENT OR THE CREDIT AGREEMENT. EACH
     PARTY HERETO (A) CERTIFIES THAT NO REPRESENTATIVE, AGENT OR ATTORNEY OF ANY
     OTHER PARTY HAS REPRESENTED, EXPRESSLY OR OTHERWISE, THAT SUCH OTHER PARTY
     WOULD NOT, IN THE EVENT OF LITIGATION, SEEK TO ENFORCE THE FOREGOING WAIVER
     AND (B) ACKNOWLEDGES THAT IT AND THE OTHER PARTIES HERETO HAVE BEEN INDUCED
     TO ENTER INTO THIS AGREEMENT AND THE CREDIT AGREEMENT, AS APPLICABLE, BY,
     AMONG OTHER THINGS, THE MUTUAL WAIVERS AND CERTIFICATIONS IN THIS SECTION
     21.
 16.  Right of Setoff. If an Event of Default shall have occurred and be
     continuing, the Borrower is hereby authorized at any time and from time to
     time, to the fullest extent permitted by law, to set off and apply any and
     all deposits (general or special, time or demand, provisional or final) at
     any time held and other Indebtedness at any time owing by such Borrower to
     or for the credit or the account of MEMC against any or all the obligations
     of MEMC now or hereafter existing under this Agreement and the Credit
     Agreement held by such Borrower, irrespective of whether or not such party
     shall have made any demand under this Agreement or the Credit Agreement and
     although such obligations may be unmatured. The rights of each party under
     this Section 22 are in addition to other rights and remedies (including
     other rights of setoff) which such party may have.

 

IN WITNESS WHEREOF, the parties hereto have duly executed this Agreement as of
the day and year first above written.

MEMC ELECTRONIC MATERIALS, INC.

By /s/ Kenneth L. Young
____________________________________
Name: Kenneth L. Young
Title: Treasurer

E.ON INTERNATIONAL FINANCE B.V., as Agent and as Initial Lender

By /s/ H. J. Wirix S.A.L. Visser
_____________________________________
Name: H. J. Wirix and S.A.L. Visser
Title: Managing Director Managing Director

By _________________________________
Name:
Title: