The influence of Cu on various metal oxide supports was investigated for the catalytic oxidation of acetaldehyde (ACA). The activity of the catalysts towards ACA conversion and the CO2 yield decrease in the order: Cu/CeO2>Cu/TiO2≈Cu/ZrO2> Cu/Al2O3>Cu/SiO2. Spontaneous adsorptive conversion of ACA to surface carboxylates, such as bridging and bidentate acetates, was detected over the basic supports CeO2, TiO2, and ZrO2. Detailed temperature-programmed studies found the high activity of Cu/CeO2 to stem mainly from the intrinsically high activity of the CeO2 support. In contrast, similar studies on Cu/TiO2 demonstrated the activity improvements imparted by Cu were predominantly additive. Despite the difference in origin of ACA oxidation activity over Cu/CeO2 and Cu/TiO2, the overall concerted effects of basicity-induced carboxylate formation and availability of surface oxygen were thought to be overriding factors crucial in the overall catalytic reactivity.