Abstract: There is provided a membrane electrode assembly including an anode gas diffusion layer included in an anode and a cathode gas diffusion layer included in a cathode, wherein the anode gas diffusion layer includes an anode gas diffusion substrate and an anode microporous layer disposed on a first surface of the anode gas diffusion substrate, wherein the cathode gas diffusion layer includes a cathode gas diffusion substrate and a cathode microporous layer disposed on a first surface of the cathode gas diffusion substrate, and wherein at least one of a strike-through ratio on a second surface of the anode gas diffusion substrate and a strike-through ratio on a second surface of the cathode gas diffusion substrate is larger than 0.2%.

Abstract: A fuel cell includes an electrolyte membrane, an anode which is disposed on one surface of the electrolyte membrane and includes an anode catalyst layer, a cathode which is disposed on the other surface of the electrolyte membrane and includes a cathode catalyst layer, and an adjustment unit which allows at least one of a relative humidity of a gas which is in contact with the anode catalyst layer and a relative humidity of a gas which is in contact with the cathode catalyst layer to be decreased down to less than 100% before a fuel is supplied at the time of starting.

Abstract: This fuel cell system [[1]] provides a fuel cell system that can be reduced in cost. This fuel cell system [[1]] includes a reformer [[11]] for reforming raw fuel using a burner [[15]] to generate reformed gas, and a CO shift converter [[12]] shaped like a tube provided integrally with the reformer [[11]] such that the reformer [[11]] is positioned in the tube, for reducing a carbon monoxide concentration in the reformed gas generated by the reformer [[11]]. In the fuel cell system [[1]], the CO shift converter [[12]] can be heated with exhaust gas from the burner [[15]] to increase the temperature thereof. Therefore, the need for a heater to increase the temperature of the CO shift converter [[12]] can be eliminated.