A hydrogen-air fuel cell using Ba0.95Ce0.9Y0.1O3-α as the solid electrolyte and porous Pt as the electrode was constructed. The Ⅰ-Ⅴ performance of the cell and the polarization characteristics of the electrodes are investigated in the temperature range of 600～1000℃. The transport numbers and conductivities of each charge carrier are also determined. It is found that the fuel cell exhibits good and stable performance. The maximum short-circuit current density drawn fom the cell is about 680 mA.cm^-^2 at 1000℃. The polarizations at both electrodes are very small and the voltage on discharging of the cell is limited mainly by the ohmic resistance of the hydrogen-air fuel cell condition. The proton transport number decreases, whereas the oxide-ion transport number increases with increasing temperature. The transport numbers of proton and oxideion are equal (0.46) at 780℃ , the proton conduction is predominant below 780℃, but the oxide-ion conduction becomes predominant above 780℃.

Key words: FUEL CELLS, PEROVSKITE TYPE STRUCTURE, BARIUM OXIDE, COBALT OXIDE, YTTRIUM OXIDE