The electrical conductivity of SrZr0.9Y0.1O3-delta was measured as a function of temperature and gas partial pressure. Extremely slow conductivity relaxation was observed below 973 K. This is attributed to slow water incorporation/evolution reaction. Unexpectedly, measured electrical conductivities increased with decrease in temperature at temperatures lower than 1023 K. Proton and oxide ion conductivities were deconvoluted from the total conductivity by simple defect-chemical analysis. At low temperatures, the actual proton conductivity was found to be several times higher than those reported. (C) 2008 Elsevier B.V. All fights reserved.