Ti-supported RuO2+ Co3O4 electrodes, prepared at 470 degrees C, were characterized by SEM, XRD, open-circuit potential (E-oc) and CV measurements. Binary mixtures has much higher areas compared with the pure oxides being the oxide morphology of mixtures with higher than 50 mol% RuO2, contents very similar to Ti/RuO2. XRD measurements of oxides showed intermediate compositions to be amorphous while those having close to pure compositions ale crystalline. E-oc,, data support that the surface electrochemistry of mixtures is controlled by the Ru-III/Ru-IV redox couple. In situ CV characterization, consistent with SEM and XRD results, showed the systematic substitution of Co3O4 by RuO2 to result in a significant increase in the current. In acid medium an intense cathodic current, attributed to CoO cathodic dissolution, is observed with Co3O4. Introduction of RuO2, however, stabilize the coatings.