The addition of an optimum amount of CeO2 (Ce/Rh = 4) to 1.0 wt% Rh/MgO promoted the catalytic partial oxidation (CPO) of methane with N-2 dilution. At the same time, it can suppress the temperature increase at the catalyst bed inlet during the CPO of methane without N-2 dilution. The Rh-CeO2/MgO (Ce/Rh = 4) has the ability to maintain a more reduced state in the CPO of methane, and this may be related to the high ability to activate methane by the synergy of Rh metal surface and partially covering Ce species. The catalyst bed of the CPO of methane consists of the initial oxidation zone and the subsequent steam reforming zone. The catalyst with higher resistance to the oxidation of Rh gives larger zone for the steam reforming and it also enables the overlap of the exothermic oxidation zone with the endothermic steam reforming zone. (C) 2009 Elsevier Inc. All rights reserved.