Several domestic activated carbons were tested as the catalyst for decomposition of methane. All the activated carbons showed similar deactivation pattern. Mass transport effect in the catalyst particles was observed and the pore mouth blocking appeared to occur noticeably especially in large particles. Between different kinds of the activated carbons, no discernible trend was observed between the initial activity and the surface area, and the initial activities lay in a relatively narrow range. The reaction orders were 0.5 and the same for different samples of the activated carbon. The activation energies were also about the same, ca. 200 kJ/mol, regardless of the kind and suppliers. These results indicate that the reaction mechanism is the same for all the activated carbons. Ashes in the activated carbons do little affect the catalytic activity. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.