Ti-supported RuO2+CO3O4 coatings were prepared by thermal decomposition at 470 degreesC. The effect of the replacement of Co3O4 by RuO2 on the service life of the coatings was investigated under galvanostatic polarisation at 0.75 A cm(-2) in 0.5 mol dm(-3) H2SO4. 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 CO3O4 by RuO2 led to an increase in the service life of the electrodes when compared to pure Co3O4. 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.