Oxygen reduction reaction (ORR) is of crucial importance in fuel cells and metal–air batteries, however, the sluggish dynamics of ORR remains a critical issue to be addressed. Here, we report the preparation of hexagonal spinel-type Mn2AlO4 nanosheets with a high BET surface area of up to 164m2 g−1 through a dealloying–annealing strategy. The Mn2AlO4 catalyst shows a good catalytic activity towards ORR in the alkaline solution, as well as much better methanol tolerance than the commercial Pt/C. Moreover, both the electrochemical measurements and density functional theory (DFT) calculations (adsorption energy, density of states, H2O2 decomposition) demonstrate that the ORR on Mn2AlO4 is a four-electron pathway. In addition, the DFT results expound the reason why the Mn2AlO4 catalyst has much better methanol tolerance than Pt/C.