A method for starting a fuel cell device having a plurality of fuel cells under frost starting conditions is provided, which comprises: establishing the presence of frost starting conditions for the fuel cell device, anode-side supplying of a hydrogen-containing reactant and cathode-side supplying of an oxygen-containing reactant in a sub-stoichiometric ratio with an oxygen deficit, maintaining the supply of the reactants in a sub-stoichiometric ratio for a given interval of time, after elapsing of the interval of time, causing the complete discharging of the fuel cells in a discharge phase, and then converting the fuel cell device to a normal mode with the supplying of the reactants according to the requirements for the given operating state and the power demand. A fuel cell device and a motor vehicle are also provided for carrying out such a method.