An apparatus for humidifying and controlling the temperature of a process gas stream; has a first humidification unit for super-saturating and heating the process gas stream at a first pre-set temperature; and a first heat exchanger for cooling the process gas stream until it reaches a second pre-set temperature, and for removing excess condensed water from the process gas stream. The apparatus can include a heater for heating the process gas stream until it reaches a third pre-set temperature.