The steam reforming of ethanol was investigated at 723 K over Al2O3, ZrO2 and Al2O3-ZrO2 supported Pt catalysts. The samples were characterized by XPS and TPR methods. The surface species formed during the adsorption of ethanol and during the catalytic reaction were investigated by DRIFT and TPD. According to the XPS results the zirconia was partially reduced during the pretreatment and the surface of the catalysts was relatively poor in Zr. Adsorbed CO and surface acetate were detected during the catalytic reaction at 723 K. It means that the formation rate of these species is higher than their decomposition or further reaction. It was established that the acetate located mainly on the Al2O3 surface and much smaller amount can be found on ZrO2 and on Al2O3-ZrO2 supported samples. The decay in the selectivity of H-2 and CO2 caused by the surface acetate species on Pt/Al2O3 decreased in the presence of ZrO2. DRIFT and TPD measurements showed that the zirconia destabilized the acetate groups which resulted in the enhanced H-2 and CO2 selectivity. The highest turnover number and yield was found on Pt/Al2O3-ZrO2 (1:3). (C) 2010 Elsevier B.V. All rights reserved.