A method and device for compressing a gas-phase medium, particularly hydrogen or natural gas, wherein the medium may have a water content up to total saturation with water and wherein the medium is compressed in a single or multiple stages in at least one liquid-filled chamber. The liquid(s) that is/are used are an ionic liquid that is not susceptible to attack by the water contained in the medium to be compressed and/or a liquid with low vapor pressure that is not susceptible to attack by the water contained in the medium to be compressed, and the compressed medium undergoes a water separation stage.