An apparatus and method for separating breathable oxygen gas from a source of gas and then humidifying the oxygen gas while preventing over humidification of the oxygen gas, the apparatus comprising a gas pathway located on a first side of a water transfer member, an oxygen gas pathway located on a second side of the water transfer member and a separator for separating the breathable oxygen gas from a gas located on the first side of the water transfer member and directing the breathable oxygen gas past the second side of the water transfer member while maintaining the pressure of the gas substantially equal to the pressure of the breathable oxygen gas to thereby humidify the breathable oxygen gas while preventing a moisture condensation in the breathable oxygen gas.