A method and a device for reducing the humidity of a gas in a housing interior, in particular in a battery housing interior, includes leading a gas through a first selectively permeable membrane and into an intermediate space. The intermediate space has the first selectively permeable membrane as an inlet and a second selectively permeable membrane as an outlet. The gas is then cooled in the intermediate space by a cooling unit such that a water vapor portion of the gas is condensed into water and the gas having a reduced water vapor content is directed through the second selectively permeable membrane into the housing interior.