The formation and stability of surface species formed in the interaction of ethanol and ethanol-water mixture with Al2O3-, TiO2- and CeO2-supported Pt catalysts were studied by FTIR. The changes of the gas phase composition during the above processes were monitored by mass spectrometer. It was found that water enhanced the stability of ethoxide surface species formed in the dissociation of ethanol on Pt catalysts and suppressed the formation of CO. Dehydrogenation of molecularly adsorbed ethanol was proposed as a key reaction step. On the temperature programmed desorption (TPD) spectra of adsorbed ethanol in the case of supported Pt there is a high temperature desorption stage, which was explained by the formation and decomposition of surface acetate species. A possible mechanism of the reaction is discussed. (c) 2005 Elsevier B.V. All rights reserved.