Temperature-programmed desorption (TPD) and oxidation (TPO) were used to study decomposition and oxidation of methanol, ethanol, acetaldehyde, formic acid, and acetic acid on a CuO/Al2O3 catalyst. The volatile organic compounds (VOCs) were adsorbed on the alumina surface and diffused to the CuO to react. Lattice oxygen in CuO is active for deep oxidation, and as lattice oxygen is depleted, diffusion of lattice oxygen to the surface limits the rate of oxidation. Supported CuO dehydrogenates and oxidizes VOCs and the order of reactivity is : HCOOH > CH3OH > CH3COOH > C2H5OH > C2H4O. Nearly all the oxygen in CuO can be extracted by VOCs. In the absence of gas-phase O-2, extraction of lattice oxygen limits the oxidation rates of acetaldehyde and acetic acid, but gas-phase O-2 rapidly replenishes the lattice oxygen. No less-reactive, partial oxidation products were detected.