Pt(0) nanoparticles stabilized by the H5PV2Mo10O40 polyoxometalate were prepared in water by a sequence of redox reactions and supported on alpha-alumina. Characterization by TEM showed an average particle size of 2.6 nm with an approximate size dispersion of about +/- 25%. EDS analysis confirmed the amounts of metal and polyoxometalate as indicated from the reaction stoichiometry. These nanoparticles were further used as catalysts for the oxidation of secondary alcohols with molecular oxygen to the corresponding carbonyl products. The oxidation of secondary alcohols was further improved by the use of Pt nanoparticles stabilized by Rh1.7PV2Mo10O40.