The effect of the carrier material on the intrinsic activity of three catalytic total oxidation reactions, namely CO oxidation and methane and propane combustion, over highly dispersed RuO₂ is studied. The carrier materials are systematically varied from ZrO₂ to CeO₂ using ultrathin CeO₂ films on ZrO₂ particles (CeO₂@ZrO₂) as the linking carrier materials that were subjected to different calcination and redox treatments. CeO₂@ZrO₂ is subjected to annealing to 900 °C, transforming the CeO₂ layer into a mixed Ce_xZr_1−xO₂ layer, and finally, after reductive treatment with H₂ at 950 °C and mild re-oxidation at 500 °C a kappa phase layer is formed on the ZrO₂ core. The catalytic CO oxidation and the propane combustion reveal pronounced dependencies on the carrier material. The variation in propane combustion activity with the carrier material is correlated with the varying surface concentration of vacant surface Ce sites, while the activity in CO oxidation is correlated with the oxygen storage capacity (OSC). Quite in contrast, the intrinsic activity and the apparent activation energy in methane combustion are less affected by the carrier material than in the other two reactions. For comparison we chose rutile TiO₂ as the carrier that is known to disperse RuO₂ quite efficiently, revealing, however, by far the lowest activity in all total oxidation reactions studied, due likely to strong metal–support interaction (SMSI).