an improved humidification system for jet - powered commercial aircraft comprising an evaporator adapted to add moisture to a gas flow , a gas flow control system for applying to the evaporator a gas flow having an internal energy sufficient to vaporize the moisture and a temperature measuring system for measuring the temperature of the gas flow exiting from the evaporator for regulating the amount of moisture added to the gas flow so as to maintain the evaporator exit temperature constant is disclosed . in a particular embodiment , the humidification system consists of a tank having an outlet duct adapted to deliver moisturized air to the passenger compartment of the aircraft , a water injection system adapted to flow water into the tank upon the temperature within the outlet duct rising above a preselected value and to terminate water flow upon the temperature falling below the preselected value , and a gas flow control system coupled to the tank and adapted to control the flow of air into the tank at a rate such that the air has sufficient internal energy to vaporize the water . an evaporator plate system is incorporated within the tank to ensure that all the injected water is vaporized before exiting the tank . additionally , a demisting filter is mounted between the evaporator plate system and the outlet duct to ensure that all particulate matter is removed from the moisturized air before leaving the tank .