ETR at Ti/TiO2-Pt electrodes under different conditions were investigated and a correlation with the electronic properties of the films was made. The effect of doping concentration, film thickness and temperature was analysed. An increase of the catalytic properties of the films was observed for increasing Pt concentration. A diminution of the electron transfer current with the film thickness was obtained. The presence of Pt within the film also produces a decrease of the energy of activation, mainly in the cathodic direction, where it remains almost constant with the potential. The results are interpreted in terms of a direct resonance tunnelling between the redox couple and the underlying metal.