In this study, temperature programmed desorption (TPD) was used to compare the reactivity of a high-surface area, monolayer vanadia/ceria catalyst with that of a 0.5 ML ceria film supported on the (1 1 1) surface of CeO2 single crystal. TPD and X-ray photoelectron spectroscopy (XPS) experiments with the vanadia/CeO2 (0 1 1) model system were carried out in an ultra-high-vacuum surface analysis system, while TPD studies for the high-surface area vanadia/ceria catalyst were conducted in a high-vacuum microbalance equipped with a mass spectrometer. The TPD studies showed similar reactivity for both samples. They were both active for the oxidation of methanol to formaldehyde and the temperature at which adsorbed methoxide intermediates underwent dehydrogenation to produce formaldehyde during TPD was found to be a function of the oxidation state of the cations in the supported vanadia layer for both samples. The similarity in the results obtained in this study from the high and low surface area samples indicates that monolayer vanadia films supported on metal oxide single crystals are excellent models of high-surface area, polycrystalline, supported vanadia catalysts. (C) 2003 Elsevier B.V. All rights reserved.