Patent ID: 8394545

Claim:
A method for operating a fuel cell system comprising a fuel cell which generates electric power for a load using a fuel gas containing hydrogen and an oxidizing gas containing oxygen, a fuel gas supplying device which supplies the fuel gas to the fuel cell, an oxidizing gas supplying device which supplies the oxidizing gas to the fuel cell, and at least one of a temperature control device which controls a temperature of the fuel cell, the method comprising steps of: generating the electric power by the fuel cell under a condition that a dew point of the fuel gas and a dew point of the oxidizing gas are lower than the temperature of the fuel cell; when stopping the fuel cell system, causing the temperature of the fuel cell to be equal to or less than at least one of the dew point of the fuel gas to be supplied to the fuel cell and the dew point of the oxidizing gas to be supplied to the fuel cell; and after the temperature of said fuel cell becomes equal to or less than at least one of the dew point of the fuel gas to be supplied to the fuel cell and the dew point of the oxidizing gas to be supplied to the fuel cell by the step of causing, cutting off the electrical connection between the fuel cell and the load.