To manage power of a fuel cell and a battery for an electronic device, an amount of power consumed by an operation module in the electronic device may be sensed. Generated voltage capacity of the fuel cell and remaining capacity of the battery may be acquired. The battery may be charged/discharged based on the sensed amount of consumed power and the generated voltage capacity of the fuel cell. A performance limit signal may be provided to the operation module if the sensed amount of consumed power exceeds a sum of the generated voltage capacity of the fuel cell and the remaining capacity of the battery. The operation module may adjust a frequency of an internal operation clock in response to the performance limit signal.