Pt-Mn3O4 catalysts with carbon black as conductive agent and support show a remarkable activity for oxygen evolution reaction because of a synergistic effect between Pt and Mn3O4. The Pt-Mn3O4/C catalyst with a weight ratio of Pt to Mn3O4 of 3:1 gives the best performance. After loading with Mn3O4, the binding energy value of Pt 4f and Mn 2p respectively has a positive and negative shift, which will accelerate to form a Pt-OH bond of the active centres. (C) 2014 Elsevier Ltd. All rights reserved.