The invention relates to a fuel cell system for mobile applications, comprising a fuel cell (1) and a DC/DC converter (2) which is coupled to the fuel cell and which can be coupled to an energy store (3). The fuel cell system is characterized in that a control/regulation unit (4) is connected to the fuel cell (1) and to the DC/DC converter (2) and that the control/regulation unit (4) comprises a performance characteristics regulator (5) that receives a value l Bz,ist of a current, a voltage value U Bz,ist from the fuel cell (1) and a value for at least one additional operating variable of the fuel cell system, that processes the received values l Bz,ist , U Bz,ist and the value for the operating variable to give a control signal and that forwards the control signal to a device (6) for controlling the operating variable. The invention also relates to an active hybrid system and to a method for the performance characteristic regulation of the fuel cell.