Abstract: A device for conditioning breathing air includes a housing (1) provided with an inlet (5) for non treated breathing air and an outlet (6) for the treated breathing air. The housing (1) contains a passive humidifier (7) and an active humidifier wherein the active humidifier includes a water supply inlet (13), a heating device for the supplied water, a membrane (12) having substantial water impermeable and water vapor permeable characteristics, and a heat exchange element (14). The membrane (12) is divided into a hydrophilic membrane (12a) and a water vapor permeable and water impermeable membrane (12b). The heat exchange element is a perforated metal plate (14) and/or a heating resistance. A method for the conditioning of breathing air includes the steps of: supplying through the inlet opening non treated breathing air, passively humidifying the supplied air through the passive humidifier, and actively humidifying the breathing air, through the active humidifier of a device.