Carbon monoxide oxidation and methane combustion were studied on Ga2O3, SnO2 or V2O5 supported on gamma-Al2O3 catalysts under the stoichiometric conditions. It was found that the catalytic activity depends on the pretreatment conditions (oxygen or hydrogen atmosphere) of the catalyst. Detailed kinetic investigations allowed determination the reaction rates and adsorption coefficients of Langmuir-type equations in the case of catalysts pretreated under oxygen atmosphere and reaction conducted with oxygen excess. (C) 2003 Published by Elsevier Science B.V.