In order to provide insight into how the support affects the reactivity of cobalt-based ethanol steam reforming catalysts, the reaction of ethanol on Co/CeO2/YSZ(100) model catalysts was investigated using a combination of X-ray photoelectron spectroscopy (XPS) and Temperature Programmed Desorption (TPD). Consistent with previous studies, metallic cobalt was found lobe active for decarbonylation of ethoxide groups, while partially oxidized cobalt containing both Co-0 and Co2+ was found to be active for ethoxide dehydrogenation to produce acetaldehyde. This partially oxidized active form of the cobalt was found to be readily formed via the reaction of vapor-deposited Co films with the reducible CeO2 support at temperatures as low as 300K. Comparisons of these results to those obtained in our previous studies of the reactivity of Co/ZnO(0001) and Co/YSZ(100) model catalysts are also presented, and the role of the support for enhancing ethanol steam reforming activity is discussed. (C) 2012 Elsevier Inc. All rights reserved.