Ni/Al2O3, Pd/Al2O3, Ni/CeO2/Al2O3 and Pd/CeO2/Al2O3 catalysts were synthesized in order to investigate the influence of the active phase on the partial oxidation of methane (POM) and the effect of CeO2 on the catalytic properties of these systems. The catalysts were characterized by XRD, XRF, BET, XPS, H-2-TPR and catalytic activity was evaluated by TPSR experiments and catalytic activity tests over 24 h on stream. The results indicated that over Ni catalysts the reaction occurs in two distinct steps: the total combustion of CH4 followed by reforming with H2O and CO2. Over Pd catalysts, the reaction follows a direct mechanism, with simultaneous formation of H-2, CO, CO2 and H2O. Regarding CeO2 effect, the results indicated it improved the CH4 conversion, CO and H-2 selectivity and catalytic activity and the resistance to deactivation. (C) 2012 Elsevier B.V. All rights reserved.