Disclosed is method of operating a fuel cell which can output an electrical maximum power dependent on the operating temperature for a given fuel gas flow, and which exhibits aging in dependence on the operating duration which brings about an increase of the electrical internal resistance with progressive operating duration. In the disclosed method, the starting value (T0) of the operating temperature for a new fuel cell or for a new fuel cell stack is typically smaller than or equal to the operating temperature, at which the electrical maximum power is achieved and the fuel cell or the fuel cell stack is regulated such that the decrease of the output electrical power as a consequence of aging is partly or completely compensated in that the operating temperature (T) of the fuel cell or of the fuel cell stack is increased with progressive aging.