Studies are presented of the kinetics and mechanism of oxygen electroreduction on CoPd catalysts synthesized on XC 72 carbon black. As shown both in model conditions and in tests with the cathodes of hydrogen-oxygen fuel cells with proton conducting electrolyte, the CoPd/C system features higher activity as compared to Co/C. It is found by means of structural analysis that CoPd alloy is formed in the course of the catalyst synthesis. This provides the higher catalytic activity of the binary systems. CoPd/C catalyst is also more stable in respect to corrosion than Pd on carbon black. Measurements on a rotating ring-disc electrode show that the CoPd/C system provides preferential oxygen reduction to water in the practically important range of potentials (E > 0.7 V). The similarity of the kinetic parameters of the oxygen reduction reaction on CoPd/C and Pt/C catalysts points to a similar reaction mechanism. The slow step of the reaction is the addition of the first electron to the adsorbed and previously protonated O-2 molecule. Studies of the most active catalyst in the fuel cell cathodes are performed. Binary PtCo catalysts (metal atomic ratio of 1 : 1) with low platinum content (7.3 wt.%) modified by phosphorus or sulfur are developed and studied. It is demonstrated that the specific activity of the PtCoS/C (Pt : S = 1 : 1) catalytic system for the O-2 reduction reaction exceeds that of a commercial Pt/C catalyst (E-TEK). The tolerance of the catalyst modified with sulfur is at least six times higher than that of Pt/C (E-TEK).