This work studies ethanol electro-catalytic oxidation by cyclic voltammetry in sulphuric acid solutions at different temperatures and concentrations, using platinum-rutenium mixtures supported in vitreous carbon as catalyzers. The results indicate that ethanol oxidation in these electrodes is irreversible, has slow kinetics, is controlled by charge transfer and is brought about by a bi-functional reaction mechanism, this being ethanol adsorption on platinum atoms and additional oxidation of species adsorbed in the presence of platinum and ruthenium oxides. Experimental results show increased catalytic activity with Pt92 Ru8 and Pt85 Ru15 electrodes, followed by reduced activity for electrodes having a greater quantity of ruthenium.