Use of carbon-based catalyst for thermocatalyfic CO2-free production of hydrogen from methane offers several advantages. In this paper, activated carbons with different textural properties and surface chemistry have been used to study the influence of these properties on the efficiency of methane decomposition. It has been shown that the initial reaction rate of decomposition is related to the surface chemistry of the catalyst, in particular to the concentration of oxygenated groups, and not to the surface area. On the other hand, the capacity to accumulate carbon before deactivation, which defines the long-term behaviour, is related to the surface area and the pore size distribution, in particular to the area in mesopores. In this way, microporrous carbons with high content of oxigenated surface groups exhibit high initial conversion rates but they become rapidly deactivated. In contrast, mesoporous carbons with high surface area provide more stable and sustainable hydrogen production. (C) 2004 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.