A kinetic model for the thermal decomposition of methane was developed by modifying a model for soot formation in combustion. The modifications consisted of adding five reactions representing surface chemistry on carbon particles. One kinetic parameter for the new surface reactions was fit to experimental data and the other parameters were determined by analogy to known gas-phase reactions. The modified model reproduces well the hydrogen concentrations at the beginning and end of recent experiments on the thermal decomposition of methane in the presence of carbon catalysts. The model predicts that increasing the pressure from 0.1 to 3.0 MPa will decrease hydrogen production with carbon catalysts by 48-60%. This prediction is robust to variations in the rate constants for the surface reactions and the rate constant for a key gas-phase reaction. (C) 2006 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.