Abstract Electrochemical activities for hydrogen oxidation on porous carbon electrodes with platinum-group bimetallic catalysts viz., Pt+Ru, Pt + Pd and Pd+Ru, in acid and alkali electrolytes, have been measured as a function of composition. Of these, carbon electrodes containing 4 wt.% Pt+6 wt.% Ru exhibit the maximum activity which is also higher than that for the individual metal catalysts. This catalyst is also active for the indirect oxidation of ammonia as well as the reduction of oxygen. X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS)_and electron spin resonance (ESR) studies reveal that the presence of Ru suppresses the formation of the oxides of platinum. X-ray and electron diffraction studies show that, unlike Pt on carbon, the catalyst particles of Pt+Ru on carbon are amorphous.