Supported group VIII (8, 9, and 10) metal catalysts, such as Fe/SiO2, Ru/SiO2, CO/SiO2, Rh/SiO2, If/SiO2, Ni/SiO2, Pd/SiO2, and Pt/SiO2 have been prepared for use in the producing of CO-free H-2 via catalytic decomposition of hydrazine. Evaluation of the catalysts was conducted in a fixed-bed continuous-flow microreactor. All of the catalysts could catalyze the decomposition of hydrazine to form H-2 and N-2 at temperatures higher than 300 degrees C. Differing from the other catalysts, the Ni, Pd, and Pt catalysts were also able to produce hydrogen with very high selectivities under rather mild conditions. Ni/SiO2 was the best catalyst owing to its high activity and excellent H2 selectivity of higher than 90% at an initial temperature of similar to 30 degrees C. The selectivity was sensitive to the reaction temperature. Low temperatures (30-60 degrees C) were favorable for producing H-2 with high selectivity. The preparation method and the support have remarkable influence on the catalytic activity and selectivity of the nickel catalysts. The reasons for such dependences are discussed according to the TPR and H-2-TPD results of the nickel catalysts. (c) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.