The oxygen reduction reaction on a graphene sheet with 6.3 % doping of nitrogen is analyzed using density functional theory calculations. It is found that all intermediates involved in the oxygen reduction reaction bind on the carbon atom next to the nitrogen dopant. The first reduction step to produce the OOH* intermediate is only moderately downhill in free energy while further reduction to O* and OH* are more exothermic. The reduction from step from O* to OH* is found responsible for the experimentally observed overpotential.