NOVELTY - The humidifier (100) has inputs (A, B) supplying dry and moisten gases, and outputs (C, D) delivering moistened and dehumidified gases. Flow plates (2, 3) include gas line structures, and port apertures include median apertures for supplying and discharging gas with an elastic seam arrangement that is arranged around the port apertures. The median apertures are branched from the port apertures, and a duct e.g. circular duct, is provided at an edge of the seam arrangement for transmission of the gas from the port apertures to the gas line structures.    USE - Operational humidifier for humidifying process gas e.g. molecular hydrogen and/or oxygen, for fuel cells in a fuel cell system (claimed) for electricity generation.    ADVANTAGE - The humidifier is manufactured in simple and cost-effective manner with improved efficiency, and minimizes the risk of damage to the aperture in the edge of the seam arrangement in a simple manner.    DETAILED DESCRIPTION - The humidifier includes water transfer media that are executed as non-strengthened membrane selected from membrane laminate Gore-Tex (RTM: Waterproof/breathable fabric), ion-soaked membrane, ionomer membrane i.e. Nafion (RTM: Sulfonated tetrafluoroethylene based fluoropolymer-copolymer) or coated and/or impregnated fabric Texapore (RTM: Breathable and waterproof material) or Venturi (RTM: Not defined). The gas line structures are selected from fabric, knitted fabric, blooming mill stand, slats, nub films, shaft or stamping structures from plastic deformable materials. The flow plates are partially made by corrosion-stable metallic materials e.g. metal sheets and/or films, that partially consist of thermoplastic, elastomer or duro plastic plastics. The gas line structures are equipped as gas line channels. An INDEPENDENT CLAIM is also included for a fuel cell system.    DESCRIPTION OF DRAWING(S) - The drawing shows a perspective view of a humidifier without a cooling circuit.    Inputs (A, B)    Outputs (C, D)    Humidifier end plates (1)    Flow plates (2, 3)    Water transfer medium (6)    Humidifier (100)