This paper presents an experimental study on the self-ignition of H-2 under different oxidation conditions and to explore how H-2 assists CO oxidation in a CO2-diluted stoichiometric stream via a catalytic reactor filled with lab-made catalyst. We characterize the light-off process by measuring the temperature time profile and radial temperature distribution at the reactor exit, the axial temperature distribution in the reactor, and the average reaction temperature for various fuel quantities under different oxidation conditions. The results show that hydrogen self-ignites in a stream of excess air, N-2-, and CO2-diluted stoichiometric O-2 without additional reactant preheating. However, self-ignition cannot be initiated if the fuel contains CO. The hydrogen mixed with CO2-diluted stoichiometric O-2 can be used in the preheating of the catalytic reactor. After the temperature stabilizes, CO or syngas can be added and oxidized in the CO2-diluted stoichiometric O-2 stream. However, because the volume fraction of CO is larger than that of H-2 in the reactant stream, oxidation cannot be sustained in the present reactor. Moreover, the conversion ratio decreases as the volume fraction of hydrogen in the reactant mixtures increases in the cases of hydrogen oxidation with inert-diluted stoichiometric oxygen. (C) 2015 Elsevier Ltd. All rights reserved.