In this contribution a model system consisting of Ni particles grown onto epitaxial CeO2 films deposited on CaF2-buffered Si(111) is presented for molecular level study of the transformations of ethanol under steam reforming conditions. The adsorption behaviour of ethanol and other stable compounds thought to be important in ethanol reforming is explored by means of photoelectron spectroscopy. Acetic acid adsorbs dissociatively and relatively strongly on both fully oxidized and slightly reduced ceria surfaces. Acetaldehyde, a key intermediate of ethanol reforming, interacts weakly with CeO2(111) while on the reduced surface stronger adsorption and a transformation towards acetate were observed. In case of ethanol, low temperature molecular adsorbates transform into ethoxy moieties around 200-250 K along with considerable surface reduction. A competitive behaviour between O-2 and ethanol emphasize the role of oxygen vacancies in the stabilization of the ethoxy groups. On the Ni-free ceria surface strongly bound ethoxy adsorbates show signs of oxidation at elevated temperatures. In the presence of Ni a certain part of the ethoxy adsorbates oxidizes towards acetate even at room temperature, which transform to carbonate upon annealing. At the same time, a significant amount of graphitic species appears on the surface, which are removed by either lattice oxygen during annealing in vacuum, resulting in heavy surface reduction or by hydroxyl groups upon annealing in water vapour. In the latter case the acetate-carbonate forming pathway becomes also suppressed, indicating that surface hydroxyl species from adsorbed water influence the decomposition route of ethanol, contribute to the elimination of carbonaceous deposits and maintain the oxidation state of ceria at the same time. (C) 2017 Elsevier B.V. All rights reserved.