Electrocatalytic water oxidation to evolve O-2 was studied on a Nafion-RuO2-Ru(bpy)(3)(2+) composite electrode. The O-2 evolution current efficiency was largely improved for the multi-component electrode over the Nafion-RuO2 and Nafion-Ru(bpy)(3)(2+) individuals. The redox mediation through the Ru(bpy)(3)(2+) was found to dominate over the RuO2 catalytic effect in the water oxidation mechanism. The specific surface area of the RuO2, which was prepared at different temperatures (300-700 degrees C), used in fabricating the composite electrode also played an important role in the overall water oxidation mechanism. Both the reaction and electrode parameters were optimized to get effective electrocatalytic current values in this study.