NOVELTY - The method for reducing corrosion susceptibility in a liquid circuit such as a fuel cell cooling circuit, which comprises a compensating reservoir (1) having an overpressure valve (7) and an underpressure valve and containing a gaseous phase (5), comprises discharging gas from the gaseous phase through the overpressure valve or flowing the gas from the atmosphere into the reservoir through the underpressure valve to stably maintain the pressure in the liquid circuit, and introducing an inert gas for rinsing into the reservoir after opening the overpressure valve or the underpressure valve.    USE - Method for reducing corrosion susceptibility in a liquid circuit such as a cooling circuit, which is useful for a fuel cell (claimed) such as polymer electrolyte membrane fuel cell and in motor vehicles with internal combustion engines.    ADVANTAGE - The method is capable of efficiently reducing the corrosion susceptibility in the liquid circuit with increased conductivity thus ensuring long service life of the liquid.    DETAILED DESCRIPTION - The method for reducing corrosion susceptibility in a liquid circuit such as a fuel cell cooling circuit, which comprises a compensating reservoir (1) having an overpressure valve (7) and an underpressure valve and containing a gaseous phase (5), comprises discharging gas from the gaseous phase through the overpressure valve or flowing the gas from the atmosphere into the reservoir through the underpressure valve to stably maintain the pressure in the liquid circuit, introducing an inert gas for rinsing into the reservoir after opening the overpressure valve or the underpressure valve, measuring the oxygen content in the gaseous phase in the reservoir, and terminating the introduction of the inert gas as soon as the oxygen content in the gaseous phase has fallen below a predetermined desired value. A regulating valve (15) is opened for introducing the inert gas and the opened regulating valve is monitored when the overpressure valve of the reservoir opens. A warning is issued when the overpressure valve not opens during opening the regulating valve. The reservoir is flowed through by the liquid in the liquid circuit. An INDEPENDENT CLAIM is included for a device for reducing corrosion-causing tendency in a liquid circuit such as a fuel cell cooling circuit.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a device for reducing corrosion susceptibility in a liquid circuit.    Compensating reservoir (1)    Gaseous phase (5)    Overpressure valve (7)    Supply container (13)    Regulating valve. (15)