A humid gas stream is dehumidified by bringing that stream into contact with the front surface of a hydrophilic capillary condenser layer that captures the water and moves it adjacent the rear surface of the capillary layer. An osmotic layer, such as a semi-permeable membrane, is disposed on the rear surface of the condenser layer, and an osmotic fluid having a low concentration of water therein, is disposed adjacent the osmotic layer. An osmotic driving force, resulting from the water concentration gradient across the osmotic layer, transports the condensed water from the condensing layer through the thickness of the osmotic layer and into an osmotic fluid. The osmotic layer also inhibits the osmotic fluid from flowing into the condenser layer.