Nitrogen-doped graphene (N-graphene) is obtained by exposing graphene to nitrogen plasma. N-graphene exhibits much higher electrocatalytic activity toward oxygen reduction and H(2)O(2) reduction than graphene, and much higher durability and selectivity than the widely-used expensive Pt for oxygen reduction. The excellent electrochemical performance of N-graphene is attributed to nitrogen functional groups and the specific properties of graphene. This indicates that N-graphene is promising for applications in electrochemical energy devices (fuel cells, metal-air batteries) and biosensors.