A pressure equalizing system (16) having two variable volume elements which interact with one another via a separating medium which can be deformed or can be moved as a function of the pressure difference, with a constant total volume, is positioned upstream of a fuel cell (11) in order to feed the fuel cell (11) with its raw-material gases (H, O). A pressure equalizing container (19) can be provided for this purpose, which is subdivided into two chambers (17H, 17O) by a separating wall (18) which can be deformed or can be moved as a function of the pressure difference; alternatively, two chambers (17H, 17O) are connected to one another by an equalizing channel (21) with a solid or liquid separating medium which can be moved therein as a function of the pressure difference. If the raw-material gas pressures are different, the separating medium is moved towards the chamber (17) with the lower gas pressure until a pressure equilibrium is achieved as a consequence of the corresponding change in the volume elements on both sides of the separating medium. In the fuel cell (11) which is fed from the chambers (17), its membrane (12), which is susceptible to fracture, therefore no longer has a destruction-critical dynamic pressure difference applied to it, without having to take control measures for this purpose in feed fittings for the raw-material gases.