אֱלֹהִים הוּא כּוֹחִי
Elohim hu Kokhi

If you meant some specific verse that's translated to English as "God is my strength" - it might be different in Hebrew, like:
Habakkuk 3:19 - "יְהוִה אֲדֹנָי, חֵילִי"
Samuel 2 22:33 - "הָאֵל מָעוּזִּי"
see first link below (Hebrew only)

Also - people translate of the name "Gabriel" (correctly) as "god is my strength", and in Hebrew it's spelled "גבריאל".
Less widespread names also mean the same:
Elitzur - אליצור
Eluzai - אלעוזי
see second link below

Elohim hu khozki

Elohim - God
hu - is (in this phrase)
khozek - strength
khozki - my strength

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Note added at 17 hrs (2007-02-15 15:13:38 GMT)
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It is quite possible in Hebrew to omit 'is'. Thus:

Elohim khozki.

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Another possibility is

Elohim uzi
אלוהים עוזי