Thermo-catalytic decomposition of methane over different carbonaceous materials was studied by monitoring the mass gain with time. The initial decomposition rates as well as the long-term behaviour of the catalyst (i.e. the carbon mass that the catalyst can accumulate before deactivation occurs) were determined for a wide range of carbon blacks (CB) with different textural properties and surface chemistry, and for a commercial activated carbon (AC). The commercial carbon black BP2000 showed the highest amount of carbon deposited, 6.13 g C-dep/g C-circle before deactivation while the higher initial carbon formation rate (r(circle)) among the different samples tested was obtained for the activated carbon CG Norit (85.9 mg C-dep/g C-circle min). The relationship between the characteristics of the carbonaceous materials and their efficiency as catalysts were also evaluated. The amount of carbon deposited until deactivation shows a linear relationship with the total pore volume of the fresh catalysts. A good correlation is also found between the initial reaction rate and the concentration of oxygenated groups desorbed as CO after a temperature-programmed desorption (TPD) experiment. (C) 2007 Elsevier B.V. All rights reserved.