Transport properties of SrCe0.95Y0.05O3-delta were studied by impedance spectroscopy and by measuring open-cell voltage (OCV) and gas permeation. Ionic transference numbers were determined by measuring the OCV of concentration cells and water vapor evolution of an O-2/H-2 fuel cell. We observed interfacial polarization on the basis of the I-V curves obtained by discharging a hydrogen concentration cell or an O-2/H-2 fuel cell. The observed high protonic conductivity (high proton and low oxide ion transference numbers) makes SrCe0.95Y0.05O3-delta a potential material for hydrogen separation. From proton conductivity measurements, under a given hydrogen partial pressure difference of 4%/0.48&%, the hydrogen permeation rate (of a dense membrane with 0.11 cm in thickness) was calculated to be approximate to 0.072 cm(3) (STP) cm(-2) min(-1) at 800 degrees C, whereas the permeation rate calculated from shea-circuit current measurements was, approximate to 0.023 cm(3) (STP) cm(-2) min(-1) at 800 degrees C. The difference between calculated and observed permeation rates is probably due to interfacial polarization.