The nature of the strongly adsorbed species of ethanol is established using in situ FTir spectroscopy. Bands in the C-H stretching region indicate the presence of CH3 and CH2 groups. The analysis of the band frequencies under consideration of the restrictions imposed by the surface selection rule, allows the assignment of the CH bands to an ethoxi species. Also, linear bonded CO and a species containing a COH group are observed. Results of DEMS experiments using isotope labelled ethanol ((CH3CH2OH)-C-12-C-13) discriminate between both carbon containing groups. DEMS data are used to calculate the percentage distribution of adsorbed species. Methane and ethane in the ratio 6:1 are produced during the reduction of the adsorbate at potentials below 0.25 V vs. rhe. Oxidation of the adsorbed residues yields carbon dioxide as the only reaction product.