The catalytic oxidation of benzene on Pd (0.5 wt%)/gamma-Al2O3-Ce catalysts with 1, 5 and 10 wt% Ce was investigated. The alumina-Ce supports were prepared by adding a Ce-nitrate precursor to an aluminum boehmite. The presence of Lewis acid sites was determined by FTIR-pyridine adsorption spectroscopy. By FTIR-CO adsorption, it was found that the presence of Ce leads to the stabilization of PdO on the supports. The presence of the PdO species on the Pd/gamma-Al2O3-Ce catalysts was confirmed by X-ray photoelectron spectroscopy (XPS). The combustion of benzene (2600 ppm) in air was carried out at atmospheric pressure. Two behaviors were observed: for the catalysts with low Ce content (1%) and without Ce, the combustion occurs in a broad temperature range 100-280 degrees C, meanwhile, catalysts with high Ce contents (5, 10%), the benzene combustion occurs in the range 220-280 degrees C. An activation treatment on Pd/gamma-Al2O3-Ce catalysts with a reactant mixture at 250 degrees C for 20 h reduces the temperature of the total combustion to 250 degrees C. A better stability on Pd/gamma-Al2O3-Ce catalysts containing 5 and 10% Ce was observed. These results suggest that the oxidative catalytic properties of cerium oxide are shown at temperatures higher than 220 degrees C, and that an activation treatment is needed to obtain an optimal Pd degrees/PdO ratio for these species. The stability showed by the catalysts is explained by the effect of the CeO2, which inhibits the deposition of carbonaceous species on the Pd surface. (C) 2007 Elsevier B.V. All rights reserved.