gamma-Al2O3-Ce catalysts were obtained by the impregnation of boehmite with cerium nitrate at different Ce contents (1, 5, 10, 20 wt%) and tested in the catalytic combustion of toluene. The catalysts annealed at 650 degrees C showed a diminution of the BET specific surface areas as a function of the cerium content. At low cerium content, the XRD spectra showed the gamma-Al2O3 phase, whereas at high cerium content, the gamma-Al2O3 phase and cerium oxide were observed. A diminution of the Lewis acidity was shown by the FTIR-pyridine absorption spectra. Both Ce3+ and Ce4+ in variable proportions were observed by XPS. It has been found that the activity for the toluene combustion can be related to the C4+/Ce3+ ratio obtained in the various catalysts. The higher the C4+/Ce3+ ratio is the higher the toluene combustion activity. (C) 2007 Elsevier B.V. All rights reserved.