A typical dense membrane of perovskite La0.8Sr0.2Co0.2Fe0.8O3-delta have been successfully prepared by citrate method using nitrate salts as cation source and citrate as an organic agent. Precursor of La0.8Sr0.2Co0.2Fe0.8O3-delta was analyzed by thermal gravimetric analysis and XRD to investigate optimum calcination temperature. Organic compound and nitrate burned out below 400 degrees C. Weight loss observed over 700 degrees C is due to decomposition of SrCO3. The recommended temperature for calcination of precursor is over 900 degrees C at which single perovskite powder is obtained without impurities. The electrical property, oxygen permeation and stability of membrane were investigated in the range of 700 to 950 degrees C. The electrical conductivity increased with increasing temperature but then decreased over 850 degrees C (20% O-2) and 750 degrees C (1% O-2) due to oxygen loss from the crystal lattice. The oxygen flux of La0.8Sr0.2Co0.2Fe0.8O3-delta membrane increased with the increasing temperature. The maximum oxygen permeation was measured to be 0.19 mL/min cm(2) at 950 degrees C. The activation energy for oxygen permeation was calculated to be 78 kJ/mol. Perovskite structure and phase did not change even after permeation test of 40 h.