Supported Pt catalysts were prepared by a colloidal deposition method including the photochemical preparation of Pt nanoparticles protected by poly(N-vinyl-2-pyrrolidone) and their deposition by liquid-phase adsorption on the various kinds of supporting materials, TiO(2), CeO(2), SiO(2), Al(2)O(3) and MgO. We investigated the effect of preparation condition on the properties of supported Pt catalysts. The amount of Pt adsorbed and Pt dispersion depended on the kinds of supporting materials. The highest Pt dispersion was obtained when they were deposited on TiO(2) (P25). The Pt dispersion did not depend on the pH value of mother liquor and the amount of Pt used in the liquid adsorption process. Pt/TiO(2) and Pt/CeO(2) showed higher activity for CO oxidation than Pt/Al(2)O(3) and Pt/MgO. (C) 2010 Elsevier B. V. All rights reserved.