NOVELTY - A water management system comprises a proton exchange membrane (PEM) having catalyst layers, porous plates positioned adjacent the catalyst layers and water transport plates (48a-b, 50a) positioned adjacent the porous plates. The reactant gases are humidified at their inlets by fins while moisture is removed in the fuel flow path and at the oxidant outlet by other fins.    USE - Used for PEM fuel cells (36a-b).    ADVANTAGE - The system humidifies the oxidant gas and the fuel gas at its inlet and condenses the oxidant gas at its outlet without the use of exterior humidifiers so preventing membrane dry out and maintaining water self-sufficiency of the fuel cell.    DETAILED DESCRIPTION - A water management system comprises a proton exchange membrane (38a-b) having an anode catalyst layer (42a) on a first major face and a cathode catalyst layer (40a) on a second major face. A first porous substrate plate (44a-b) is positioned adjacent the anode catalyst layer and a second porous support plate (46a-b) is positioned adjacent the cathode catalyst layer. A fuel path (39) directs fuel into, through and out of the first porous support plate for a reaction with the anode catalyst layer of the PEM component. An oxidant gas path (29) directs an oxidant gas into, through and out of the second porous support plate for a second reaction with the cathode catalyst layer. It includes an oxidant gas inlet and outlet. A coolant path directs water into, through and out of the second porous support plate for cooling the fuel cell. It includes a water inlet and outlet. The oxidant gas is humidified at their inlets by fins while moisture is removed in the fuel flow path and at the oxidant outlet by other fins.    DESCRIPTION OF DRAWING(S) - The figure shows a more detailed cross-sectional view of adjacent PEM cells with the water management system.    Oxidant gas path (29)    Fuel cells (36a-b)    PEM (38a-b)    Fuel path (39)    Cathode catalyst layer (40a)    Anode catalyst layer (42a)    First substrate plate (44a-b)    Second support plate (46a-b)    Water transport plates (48a-b, 50a)