Cu particles have been deposited on TiO2 by incipient-wetness impregnation followed by low-temperature (400degreesC) calcination/reduction, and the metallization process leads to significant enhancement in photocatalytic activity of TiO2 for H-2 production from aqueous methanol solution. The activity exhibits up to 10-fold enhancement at the optimum loading of similar to 1.2 wt% Cu. Spectroscopic studies indicated that the Cu particles were oxidized during reaction to have a valence lower those of thermally oxidized particles, which showed inferior activities. Dissolution of Cu ion in TiO2 lattice, in contrast, resulted in reduction in photocatalytic activity. (C) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.