Styrene-divinylbenzene copolymer-supported Pt, fluorinated (10, 28 or 65% F) supported Pt and activated carbon-supported Pt-Cu were studied in the prepn. of (a) octyl-, (b) hexadecyl-, and (c) (3-glycidoxypropyl)-bis(trimethylsiloxy)methylsilanes. The selectivity toward each product was 100%. A 1-hr. reaction gave the b-product in 94-98% (max.) yield. The copolymer-supported catalyst and bimetallic Pt-Cu catalyst were more active than fluorinated carbon-supported Pt catalysts.