The kinetics of iso-octane steam reforming over a nickel based catalyst has been examined as a function of iso-octane and steam partial pressures at various temperatures. The reaction order is 0.2 with respect to iso-octane, suggesting strong coverage of nickel by iso-octane and 0.5 with respect to steam, indicating dissociative adsorption of steam. Indeed, a Langmuir-Hinshelwood (LH) mechanism requiring the dissociative adsorption of iso-octane and steam on two different sites appeared to be the most plausible pathway for the steam reforming reaction. The activation energy of 44 +/- 2.2 kJ mol(-1) estimated from the LH model is consistent with the trend previously reported for other lower hydrocarbons. (C) 2003 Elsevier B.V. All rights reserved.