January 17, 2001 E.ON International Finance B.V. Strawinskylaan 3111, 1070 ZX Amsterdam The Netherlands Attention: Mr. Peter Pels E.ON AG Bennigsenplatz 1 D-40474 Dusseldorf Germany Attention: Dr. Michael Bangert Ladies and Gentlemen: Reference is...

                               January 17, 2001


E.ON International Finance B.V.
Xxxxxxxxxxxxxx 0000,
0000 XX Xxxxxxxxx
Xxx Xxxxxxxxxxx
Attention: Xx. Xxxxx Xxxx

E.ON AG
Xxxxxxxxxxxxxx 0
X-00000 Xxxxxxxxxx
Xxxxxxx
Attention: Xx. Xxxxxxx Xxxxxxx


Ladies and Gentlemen:

     Reference is made to (a) the Credit Agreement dated as of September 22,
2000 (the "Credit Agreement") between MEMC Electronic Materials S.P.A. ("MEMC
Sub") and E.ON International Finance B.V., formerly called VEBA International
Finance B.V. ("Finance") and (b) the Guaranty of MEMC Electronic Materials, Inc.
("MEMC") dated September 22, 2000, relating to, among other things, the Credit
Agreement (the "Guaranty").

     MEMC, E.ON AG and Finance hereby agree that if on or prior to September 1,
2001, the entire principal amount of 80 million euro, plus all accrued interest
and any other outstanding amounts owing under the Credit Agreement have not been
paid in full to Finance, then (i) MEMC shall cause MEMC Sub to execute and
deliver to Finance, and Finance shall execute and deliver to MEMC Sub, an
amended and restated Credit Agreement, and (ii) MEMC shall execute and deliver
to Finance an amended and restated Guaranty. The amended and restated Credit
Agreement and the amended and restated Guaranty shall amend and restate the
Credit Agreement and the Guaranty, respectively, in a manner substantially the
same as the amended and restated credit agreements between E.ON AG and MEMC
effective as of December 31, 2000, including, without limitation, the extension
of the maturity date of the Credit Agreement for an additional twelve months
until September 22, 2002.


                                        Very truly yours,

                                        MEMC Electronic Materials, Inc.


                                        By: /s/ Xxxxxxx X. Xxxxx
                                           ----------------------------------
                                           Name:  Xxxxxxx X. Xxxxx
                                           Title: Treasurer

ACCEPTED AND AGREED:

E.ON INTERNATIONAL FINANCE B.V.


By: /s/ H. J. Wirix and X. X. X. Xxxxxx
   -------------------------------------------
   Name: H. J. Wirix and X. X. X. Xxxxxx
   Title: Managing Director/Managing Director


By:_____________________________________
   Name:
   Title:

                                    Page 1


E.ON AG


By: /s/  Xxxxxx Xxxxxxxxxxx
   ---------------------------------------
   Name:  Xx. Xxxxxx Xxxxxxxxxxx
   Title: Chief Financial Officer


By: /s/ Xxxxxxx Xxxxxxx
   ---------------------------------------
   Name:  Xx. Xxxxxxx Xxxxxxx
   Title: Vice President

                                    Page 2