Platinum photodeposition on TiO2 from methanolic solution of chloroplatinic acid (CPA) is investigated to determine the conditions that give optimum photocatalytic activity towards dehydrogenation of methanol. Conditions favoring nucleation of Pt islets rather than their autocatalytic growth enhance the catalytic activity. Photoplatinization from idoplatinic acid, adsorbing more strongly on TiO2 than CPA produced more active Pt/TiO2 catalysts. The best catalyst prepared from CPA yielded H-2 from 12.5% methanol solution at a quantum efficiency of 23.9% whereas for idoplatinic acid based catalysts, the quantum efficiency increased to 42.5%. (c) 2006 Elsevier B.V. All rights reserved.