NOVELTY - A high temperature fuel cell system has upper and lower sheet gaskets (51, 52) comprising respective inner portions (53, 54) covering an extending portion (12) of electrolyte membrane and outer portions (55, 56) combined with each other; rubber gaskets (71, 72) disposed on the outer portions of the sheet gaskets to seal a space between the conductive plates and the sheet gaskets; and adhesive (60) to seal the outer portions of the sheet gaskets, where ends of the inner portions of the sheet gaskets are respectively disposed between edges of electrodes and electrolyte membrane.    USE - For use at high temperature.    ADVANTAGE - The fuel cell system has improved sealing properties in consideration of the shrinkage and expansion of membranes.    DETAILED DESCRIPTION - A high temperature fuel cell system comprises:    (1) membrane electrode assemblies (MEAs) having an anode electrode (20) and a cathode electrode (30) disposed on respective sides of an electrolyte membrane (10), the electrolyte membrane having phosphoric acid as a hydrogen conductive material;    (2) conductive plates (41, 42) respectively contacting the anode and cathode electrodes;    (3) upper and lower sheet gaskets comprising respective inner portions covering an extending portion of the electrolyte membrane and outer portions combined with each other, where the extending portion of the electrolyte membrane is exposed from the anode and cathode electrodes;    (4) rubber gaskets that are respectively disposed on the outer portions of the upper and lower sheet gaskets to seal a space between the conductive plates and the upper and lower sheet gaskets; and    (5) adhesive to seal the outer portions of the lower sheet gasket and upper sheet gasket, where ends of the inner portions of the upper and lower sheet gaskets are respectively disposed between edges of the anode and cathode electrodes and the electrolyte membrane.    An INDEPENDENT CLAIM is also included for forming a unit cell (100) of high temperature fuel cell system, comprising:    (A) disposing an anode electrode and a cathode electrode on respective sides of an electrolyte membrane to provide MEA;    (B) disposing conductive plates in respective communicating relation with the anode and cathode electrodes;    (C) covering an extending portion of the electrolyte membrane with respective inner portions of upper and lower sheet gaskets and combining outer portions of the upper and lower sheet gaskets with each other, where the extending portion of the electrolyte membrane is exposed from the anode and cathode electrodes;    (D) disposing sealing gaskets respectively on the outer portions of the upper and lower sheet gaskets to seal a space between the conductive plates and the upper and lower sheet gaskets; and    (E) sealing the outer portions of the upper and lower sheet gaskets, where ends of the inner portions of the upper and lower sheet gaskets are respectively disposed between edges of the anode and cathode electrodes and the electrolyte membrane.    DESCRIPTION OF DRAWING(S) - The figure is a cross-sectional view of a unit cell and unit cells of a high temperature fuel cell.    Electrolyte membrane (10)    Extending portion (12)    Anode electrode (20)    Cathode electrode (30)    Conductive plates (41, 42)    Sheet gaskets (51, 52)    Inner portions (53, 54)    Outer portions (55, 56)    Adhesive (60)    Rubber gaskets (71, 72)    Unit cell (100)