The influence of SBA-15 substrate modified with CeO2 on the catalytic response of supported gold catalysts in the CO oxidation reaction was investigated. The mesoporous CeO2/SBA-15 materials (5, 10, 15 and 20 wt% of CeO2) were prepared by incipient wetness impregnation of synthesized SBA-15 substrate whereas the supported gold catalysts were prepared by deposition-precipitation method. The dried Au/SBA-15 and Au/CeO2/SBA-15 catalysts were characterized by elemental analysis (EDX). N-2 adsorption-desorption isotherms, X-ray diffraction (XRD), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), high resolution transmission electronic microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS) and their catalytic activity was investigated by the temperature-programmed CO oxidation reaction performed in temperature range 26-205 degrees C. Catalytic activity was found to increase with the CeO2 loading even though this increase was not linear: the highest catalytic activity was observed for the catalyst loaded with 10 wt% CeO2. This result was explained in terms of the combined effects of the higher stability of gold particles on the support. It was found that the Au nanoparticles in the CeO2/SBA-15 substrates could be stabilized more efficiently than those on Ce-free SBA-15 material. For the Ce-containing catalysts, a superior performance of the Au/10%CeOx/SBA-15 catalyst was related to multiple factors such as (i) highest dispersion of Au species on the support surface (by XPS and HRTEM), (ii) highest surface exposure of the Au delta+ species (by XPS), and (iii) probably a synergetic effect between the gold nanoparticles and the CeO2 nanoparticle size (by XRD, UV-vis and HRTEM). (C) 2010 Elsevier B.V. All rights reserved.