An electrochemical analysis was conducted with respect to a hydrogen membrane fuel cell with SrZr 0.8In 0.2O 3- δ electrolyte, which is a new type of fuel cell featuring an ultra-thin proton conductor supported on a dense metal anode. Most of the voltage loss derives from the cathode and the electrolyte, and a small amount of anode polarization was observed only in regions with high current density. The cathode polarization was approximately an order of magnitude lower than that of SOFCs. Furthermore, the conductivity of the film electrolyte was almost identical to that of the sinter at 600 °C; however, it was several times as large at 400 °C. A TEM micrograph revealed that the film electrolyte consists mainly of long columnar crystals, and this crystal structure can be related to the conductivity enhancement below 600 °C.