Ti-supported RuO 2 +Co 3 O 4 coatings were prepared by thermal decomposition at 470 o C. The effect of the replacement of Co 3 O 4 by RuO 2 on the service life of the coatings was investigated under galvanostatic polarisation at 0.75 A cm - 2 in 0.5 mol dm - 3 H 2 SO 4 . The electrode deactivation mechanism, using the oer as the model reaction, was investigated by recording cyclic voltammograms (CV) and electrochemical impedance spectra (EIS) at pre-established times during electrode anodization. The service life showed a strong dependence on electrode composition. Replacement of Co 3 O 4 by RuO 2 led to an increase in the service life of the electrodes when compared to pure Co 3 O 4 . Analysis of the behaviour of the EIS and CV parameters made it possible to describe an overall deactivation mechanism. The inductance observed in the high frequency domain showed a dependence on corrosion time and was attributed as having its origin in the complex rugged/porous microstructure of the oxide coatings due to the complex route followed by the charge carriers.