This work presents the preparation and characterization of dimensionally stable anodes (DSA) of nominal composition Ti/Ru0.3Ti0.7O2, modified by electrodeposition of small amounts of Pt or PbO2. Partial coverage of the anode surface with the modulator metals allowed us to change the coating properties in a significant way. The purpose of this preparation was to modulate the anode characteristics to enhance its electrocatalytic activity and obtain the maximum advantage from the mechanical resistance of DSA-type anodes. This new composite was applied to formaldehyde electro-oxidation. Bulk electrolysis experiments were carried out in acid medium. Electrode efficiency with respect to the formation of the more oxidized compound (CO2) was shown to be related with the amount and distribution of electrodeposited platinum over the DSA surface. The DSA modified with PbO2 (100 mu g cm(-2)) was more efficient than bare DSA. However, the amount of CO2 obtained with the former electrode was still lower than that obtained with the platinum-modified ones. Bulk electrolysis results showed that DSA is not an inert substrate once it is clear that the same amount of electrodeposited catalyst on the RuO2-TiO2 substrate increases CO2 formation. (c) 2006 The Electrochemical Society.