The perovskite-type oxides, La1-xSrxFe0.5Mn0.5O3-d and Sr1-wFeyMn1-yO3-d, were synthesized and investigated regarding their electrical conductivity and oxygen permeability. La1-xSrxFe0.5Mn0.5O3-d for x = 0-0.5 exhibited semiconducting behavior below 400 degrees C and all the compounds exhibited metallic behavior above 500 degrees C, indicating electronic conduction. Increase of Sr content for La1-xSrxFe0.5Mn0.5O3-d and Fe3+/Mn4+ ratio for SrFeyMn1-yO3-d led to increase in oxygen vacancies in the perovskite lattice and enhanced oxygen permeability. Introduction of cation vacancies also enhanced the permeability of Sr1-wFe0.8Mn0.2O3-d and Sr0.8Fe0.8Mn0.2O3-d had the highest oxygen permeation rate of the compounds synthesized in this work. (c) 2005 Elsevier B.V. All rights reserved.