Decomposition of methane into carbon and hydrogen was studied on Ni/SiO2 catalysts using 5-90 wt% Ni loadings. The catalytic activities and the lifetimes of the catalysts for the reaction were examined and are discussed. The relation between the catalytic performances and the characterization of fresh and used catalysts discussed on the basis of the results of SEM, XRD, TPR, DTA, TGA and carbon analysis. Among all Ni loadings, 30 wt% Ni on silica has shown to have good activity and longevity at 600 degrees C. (C) 2007 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.