A fuel cell system which has a high temperature fuel cell stack (1) with current diverters (5) and a reformer and/or an afterburner (6), the current diverters (5) being connected with low temperature connecting elements (10) for current delivery. The current diverters (5) are in thermal contact with the reformer and/or afterburner (6) between the high temperature fuel cell stack (1) and the low temperature connecting elements (10). The thermal contact prevents cooling of the HTFC stack 1 on its ends in the vicinity of the connecting points of the current diverters (5) and ensures effective conversion and uniform transport of the fuel.