The Müller Channel Humidity Sensor measures the air humidity by means of a humidity dependent capacitor. The capacitive humidity measuring element, manufactured with thin-film technology, is composed of a carrier panel, on which the electrodes are deposited, topped by a hygroscopic polymer layer. The hygroscopic polymer layer absorbs the water molecules out of the medium (air) to be measured, or delivers them and consequently alters the capacity of the capacitor. In the following electronic circuit the alteration of the capacity is processed into the standardised signals 0…20 mA, 0…10 VDC or 4…20 mA by an integrated signal pre-processing. The measuring element is protected by a protecting basket. The sensors are designed for an unpressurised system, the measuring medium is non-aggressive and non-condensing air. Optionally the sensors have a semiconductor temperature sensing device in order to acquire the temperature simultaneously. Its measuring values are also converted into the standardised signals 0…20 mA, 0…10 VDC or 4…20 mA.