In the present work a zinc oxide-supported nickel catalyst was investigated for the steam reforming of ethanol. Comparison was made to the nickel catalysts supported on La2O3, MgO and gamma-Al2O3. Experimental results showed that Ni/ZnO is superior among the catalysts. especially in terms of selectivity and distribution of byproducts. Influential factors, such as reaction temperature, water to ethanol molar ratio, liquid hourly space velocity (LHSV) and Ni loading, were investigated using a Ni/ZnO catalyst. The conversion was always complete at temperatures above 330 degrees C, regardless of the changes in other reaction conditions. However, the selectivity to hydrogen was increased with the increase in temperature, H2O/EtOH molar ratio and Ni loading. A selectivity of up to 95% was reached under conditions of T = 650 degrees C, LHSV = 5.0 h(-1), H2O/EtOH ratio = 8, and Ni loading = 20 wt%. The effect of the influential factors on the side reactions and the distribution of byproducts was also discussed. (c) 2005 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.