Abstract: In order to provide a fuel cell device, including a fuel cell stack that includes electrochemically active cathode/electrolyte/anode units, and a reformer for producing a fuel gas for the fuel cell stack from a starting fuel, wherein the fuel cell stack is configured to have the fuel gas produced by the reformer and an oxidizing agent supplied to it, in which the thermomechanical loads in the heating phase are lessened and/or it is made possible to shorten the heating phase, it is proposed that the fuel cell device should include at least one heat transfer device which is configured to have the fuel gas and the oxidizing agent flow through it, upstream of the cathode/electrolyte/anode units of the fuel cell stack.