Abstract Glassy carbon electrodes can be modified persistently with heteropoly and isopoly oxometalates and with tungstate anion. The present communication describes such a modification using 17-tungsto, 1-molybdo-diphosphate. In neat 0.5 M H 2SO 4, this modified material is characterized by a persistent surface redox couple. Activation of this modified glassy carbon surface with respect to the hydrogen evolution reaction, to the oxygen reduction process which is proton consuming or vis à vis the simple outer-sphere electrode reaction of hexammine ruthenium(III) cation, is demonstrated. For the hydrogen evolution reaction and oxygen reduction process, a platinized-platinum-like behaviour has been observed. For the ruthenium complex, a comparison has been made with freshly polished glassy carbon and with gold and it appears that on the modified surface, the apparent electron transfer rate constant is as high as on the gold surface. The activation is durable.