In this study, we have investigated the oxygen reduction reaction (ORR) activity and durability of Co-based catalysts mechanistically. CoPt/C catalysts with a Pt loading of 7 wt% and Au modification have been prepared and shown excellent ORR performance. The various as-prepared CoPt/C and CoPtAu/C catalysts have about 2.6-9.2 times higher mass activity than commercial Pt/C. The mechanistic insight obtained by density functional theory calculations has shown that the enhanced activity is attributable to the fact that Co-based catalysts can easily dissociate surface O2∗ without the high-barrier protonation step and efficiently remove the dissociated O∗. The improved stability, 1000th decay = 14.6%, corresponds to the fact that the core Au can resist the shrinkage of surface Pt during the accelerated durability test.