The invention relates to a device (1) having at least one fuel cell (2) and a DC/DC converter (3) assigned to the latter. A variable voltage generated in the fuel cell (2) is converted, by means of the DC/DC converter (3), into a DC voltage for a system (4) to be supplied. The DC/DC converter (3) is designed to capture internal characteristic variables of the fuel cell (2). Operating states of the fuel cell (2) are captured and/or controlled in dependence on these characteristic variables.