TECHNOLOGY FOCUS - ELECTRICAL POWER AND ENERGY - Preferred System: In the high-temperature fuel cell system, the radial outer shell (4, 5) where the radial shell is made from a material with low thermal conductivity and/or an additional insulation unit (2) is constructed onto the shell (4, 5). The heat-reflecting layer is attached to an inner and/or outer wall of the shell (4, 5). The inner insulation unit (2) is a passive thermal insulation unit and, in particular, an evacuated hollow space. Between the radial outer shell (4, 5) and inner thermal insulation unit (2) at least two hollow spaces (3a, 3b) are present, which are divided by at least one separating wall (7). The different fluids and/or fluids of different temperatures can be fed through the hollow spaces (3a, 3b). The gas channels (8) are passed through the interior of the thermal insulation unit (2) and the gas channels (8) dividing the thermal insulation unit into several layers and/or areas. The layers and/or areas are made of different materials. One or several fuel cell(s) (1) and/or at least one of the fuel cell system components (25, 26) are directly enclosed by a system (9), which is designed for the heat exchange; or such a heat exchanging system (9) is located immediately next and/or connected by fluid flow to the fuel cell(s) (1) and/or the at least one fuel cell system component (25, 26) and the system (9) is arranged within the inner thermal insulation unit (2). The reducing fluid or fluid mixture for the operation of the fuel cell(s) (1) and/or the fuel cell system components (25, 25) is fed through the hollow space/spaces (3, 3a, 3b). The oxidizing fluid or fluid mixture for the operation of the fuel cell(s) (1) and/or the fuel cell system components (25, 25) is fed through the hollow space/spaces (3, 3a, 3b). The exhaust gas of the fuel cell(s) (1) and/or the fuel cell system components (26, 25) is fed through the hollow space/spaces (3, 3a, 3b). The heat exchanging system (9) and at least one of the fuel cells (1) and/or fuel cell components (25, 26) are manufactured as one component. At least one hollow space (3, 3a, 3b) is connected to a depression-generating element, in particular a jet pump and/or a venturi nozzle (24). The fuel cell system component is a burner (25) or a reformer (26). The inner insulation unit (2) consists of a composite material with one component having its melting point or melting region close to the targeted operating-temperature. The fluid fed through the hollow space (3) is fed to a chiller or a peltier-element to actively prevent peripherical-parts like accumulators or the shell-surface from overheating.