In this work gold catalysts supported over SBA-15 with different CeO2 loadings (5-30 wt%) were prepared, characterized by N-2 physisorption analyses, SAXS, XRD, STEM and XPS techniques and their catalytic performances were evaluated in the CO oxidation, chosen as reaction test. Over a selected catalyst, Au/CeO2(20 wt%)-SBA-15, the effect of CO2 and of the mixture (CO2 + H2O) on the CO conversion to CO2 was also evaluated. Characterizations by SAXS, XRD, STEM and XPS were carried out on selected spent catalysts after CO oxidation. The results were discussed in terms of relationship between morphological, structural, electronic and catalytic properties as a function of the ceria loading. The CO oxidation activity was strongly affected by gold particle size and gold/ceria interface as well. For gold catalysts supported on ceria-doped SBA-15. the oxygen vacancies in ceria likely act as nucleation sites for gold anchoring and stabilization against sintering. The optimum of the catalytic performances was found for 20 wt% ceria loading, likely due to the optimum synergistic interaction between highly dispersed defective ceria oxide and nanosized gold. (C) 2012 Elsevier B.V. All rights reserved.