A new electrode catalyst prepared using methane gas by microwave-assisted catalytic decomposition has been developed. The prepared catalyst has a graphene-covered nickel particle (GCNP) structure. GCNPs were fabricated as a powder microelectrode. Oxygen reduction activity was evaluated using an electrochemical potential sweep method. This activity was evaluated by comparing the oxygen reduction reaction (ORR) at the GCNP and commercially available Pt/C. The ORR at the GCNP was found to be similar to that of Pt/C in neutral solution. In acidic solution, the GCNP exhibited higher corrosion resistance than a nickel particle. The result was due to the prepared graphene. (C) The Electrochemical Society of Japan, All rights reserved.