Support effect for the catalytic activity of liquid phase reforming of methanol with water was investigated over various supported Pt-Ru bimetallic catalysts. The SiO2, TiO2, Al2O3, MgO, CeO2 and ZrO2 were used as support materials by conventional impregnation method. Basic oxide supports improved the selectivity to CO2, whereas acidic supports suppressed the catalytic activity and selectivity. The Pt-Ru/TiO2 catalyst exhibited highest activity and selectivity for CO2, which were improved by higher temperature reduction. The improved activity and selectivity were attributable to the occurrence of SMSI state and Pt-Ru alloy, respectively. The reforming reaction over Pt-Ru/TiO2 catalyst proceeded through partially dehydrogenated HCOOCH3 and HCOOH intermediate with the similar mechanism as that over SiO2 supported Pt-Ru catalyst. (c) 2005 Elsevier B.V. All rights reserved.