The behavior Of Pt/SiO2 and tin-modified Pt catalysts, PtSn-OM (organobimetallic catalyst) and PtSn-BM (bimetallic catalyst), in the hydrogenation of aromatic ketones: acetophenone, 3,4-dimethoxyacetophenone, benzophenone and chalcone, was studied. With PtSn-OM and PtSn-BM systems, results showed high selectivity, mostly exceeding 90%, towards the corresponding alcohols. In the case of acetophenone hydrogenation with PtSn-OM, selectivity to I-phenyl-ethanol (1) is nearly 100% and both activity and selectivity are maintained after three reusing cycles. The electronic effect of ionic tin in the vicinity of platinum atoms is present in both systems; besides, the existence of SnBux fragments anchored to the metallic surface in PtSn-OM catalyst, favors the adsorption and activation of the C=O group of ketones, leading to high values of selectivity to the desired products. (C) 2004 Elsevier B.V. All rights reserved.