In the present work the reaction of biomass-derived ethanol steam reforming for hydrogen rich gas streams production, over a commercial alumina supported palladium catalyst was investigated. In particular, the dependence of the catalytic activity and selectivity on reaction temperature, HO/EtOH molar ratio and contact time was studied. In order to evaluate the catalytic stability long-term experiments were also performed. It was found that hydrogen selectivity was proportional to the H2O/EtOH molar ratio and ethanol was completely converted even at relatively low temperature values. Hydrogen selectivities up to 95% were obtained at temperature values close to 650degreesC. It was also observed that for the examined H2O/EtOH molar ratios, carbon monoxide concentration exhibits for thermodynamic reasons a minimum at a temperature value close to 450degreesC. Furthermore, carbon formation was found to be negligible even for H2O/EtOH molar ratio equal to the stoichiometric one. On the contrary, as water to ethanol ratio in the feed stream was decreased below the stoichiometric, carbon rate formation was increased resulting in catalyst deactivation. (C) 2003 Elsevier B.V. All rights reserved.