Compositions in the system La1-xSrxFe1-xMyO3-delta (M = Cr, Ti) where 0.2 < x < 0.8 and 0.2 < y(Ti) < 0.5 and 0.1 < y(Cr) < 0.3 were investigated to determine their suitability as oxygen membrane materials. Oxygen flux was measured as well as electrical conductivity, thermal and chemical expansion and chemical reactivity with zirconia. The microstructures of all samples were analyzed before and after flux measurements. High oxygen flux values and electrical conductivities were observed for compositions with high Sr and Fe contents, while greater stability and lower thermal and chemical expansivity were observed for compositions with lower Sr contents and Ti substituted on B-site. (C) 2007 Elsevier B.V. All rights reserved.