(US5366818-A)      The fuel cell system comprises (a) an H2-contg inlet fuel stream, (b) an O2-contg inlet oxidant stream, (c) a fuel stack comprising at least one fuel cell composed of (i) an anode with an inlet to direct the inlet fuel stream to the catalytically active portion, for prodn of cations, (ii) a cathode with an inlet to direct the inlet oxidant stream to the catalytically active portion to produce anions which react with the cations to form water, (iii) a cation exchange membrane between the anode and cathode, facilitating migration of cations from anode to cathode and isolating the fuel and oxidant streams, (iv) a means to conduct electric current between the electrodes, and (v) means to maintain the partial pressure of water vapour in the outlet fuel stream below the satn. pressure, and (d) a water separator to remove water from the outlet fuel stream to produce a dehumidified fuel stream and a water stream.    ADVANTAGE -   A large proportion of water accumulated at the cathode is absorbed in the outlet fuel stream (claimed). Pure and impure fuel and oxidant streams can be used.    (JP8507405-W)      System comprises: an H2 fuel stream; an O2 oxidant stream; a fuel stack comprising a catalytic anode for the fuel stream, a catalytic cathode for the oxidant stream, a cation exchange membrane for migration of cations from the anode to the cathode and for isolating the fuel stream from the oxidant stream and means for maintaining the pp of water vapour in the outlet fuel stream below the satn. pressure of the water vapour in the stream; and a water separator for removing water from the outlet fuel stream (18), so that most of the water accumulated at the cathode is absorbed in the outlet fuel stream. Modified embodiments of the system are claimed.    The stoichiometry of the inlet oxidant stream is less than 2.0; where the oxidant is pure O2, the stoichiometry is 1.0 and all the O2 is consumed; where it is impure O2, the outlet stream is dehumidified and vented. Where the inlet fuel stream is pure H2, the dehumidified outlet stream is recycled; where it is impure hydrocarbon conversion H2, the dehumidified outlet stream is vented.    USE/ADVANTAGE -   As e.g. a power source for electric vehicles. Water accumulated at the cathode is removed in the outlet fuel stream of the anode so that recirculation of the oxidant stream is avoided. The system can be used with pure fuel streams (e.g. bottled H2) or impure fuel streams (e.g. hydrocarbon conversion streams), and with pure oxidant streams (e.g. bottled O2) or impure oxidant streams (e.g. air).    (EP671057-B1)      System comprises: an H2 fuel stream; an O2 oxidant stream; a fuel stack comprising a catalytic anode for the fuel stream, a catalytic cathode for the oxidant stream, a cation exchange membrane for migration of cations from the anode to the cathode and for isolating the fuel stream from the oxidant stream and means for maintaining the pp of water vapour in the outlet fuel stream below the satn. pressure of the water vapour in the stream; and a water separator for removing water from the outlet fuel stream (18), so that most of the water accumulated at the cathode is absorbed in the outlet fuel stream. Modified embodiments of the system are claimed.    The stoichiometry of the inlet oxidant stream is less than 2.0; where the oxidant is pure O2, the stoichiometry is 1.0 and all the O2 is consumed; where it is impure O2, the outlet stream is dehumidified and vented. Where the inlet fuel stream is pure H2, the dehumidified outlet stream is recycled; where it is impure hydrocarbon conversion H2, the dehumidified outlet stream is vented.    USE/ADVANTAGE -   As e.g. a power source for electric vehicles. Water accumulated at the cathode is removed in the outlet fuel stream of the anode so that recirculation of the oxidant stream is avoided. The system can be used with pure fuel streams (e.g. bottled H2) or impure fuel streams (e.g. hydrocarbon conversion streams), and with pure oxidant streams (e.g. bottled O2) or impure oxidant streams (e.g. air).