For thermodynamic reasons, CO2 has always been considered as inert at mild reaction temperatures (similar to 300 degrees C). In this study, we show that CO2 may be used as a valuable compound for the catalytic combustion of methane (CCM), if ceria-based materials are used as support for the palladium active phase. Adding CO2 in the feed significantly improves performances of ceria-zirconia supported catalysts. On the contrary, catalytic performances are inhibited on Pd/gamma-Al2O3. Inhibition can be avoided by mixing the Pd/gamma-Al2O3 catalyst with some CeO2 evidencing cooperation phenomena between both catalysts. In situ DRIFTS experiments show that the inhibition of the alumina-supported catalyst is not due to formation of carbonates species. After an in situ reducing pre-treatment, pure CO2 is able to rapidly oxidize reduced Pd/Ce0.21Zr0.79O2 catalyst at 300 degrees C. Dissociation of CO2 on Ce0.21Zr0.79O2 would be responsible for the oxidation process. Thus, CO2 helps in replenishing the O reservoir (OSC) of the Ce-Zr-O support which is normally consumed by reductants such as CH4, H-2 or other HC's. XPS experiments show enrichment in oxygen species bound to Ce (Low BE O1s) on the surface of ceria-zirconia when working in the presence of CO2. Implications of these results on the behavior of ceria-containing catalysts can be important for practical applications, e.g., in automotive exhaust catalysis. (c) 2006 Published by Elsevier B.V.