A perovskite-type Ba-(x=0.2,Ba-0.5,Ba-0.8)Sr1-xCo0.8Fe0.2O3-delta (BSCFO) was synthesized and used as an oxygen permeable membrane. The oxygen permeation flux of the membranes with a thickness of 4 mm was determined at different temperatures, feed flow rates (air), and helium flow rates between (650 and 950) degrees C, (100 and 200) mL.min(-1), and (40 and 80) mL.min(-1), respectively. Experimental results showed that increasing helium flow rate increases oxygen permeation flux due to reduction of oxygen partial pressure in the permeate side. However, it was realized that oxygen permeation flux could be affected by air flow rate in the feed side. The dependency of oxygen permeation flux oil air flow rate decreases at air flow rates higher than 150 mL.min(-1). Although XRD and EDS results showed that the surface of the BSCFO membranes exposed to air for 75 h is almost similar to the surface of the fresh membranes in composition and structure, there are differences between the fresh membrane surface and the membrane surface exposed to helium, due to the reduction reaction. Comparing SEM images of the used membrane surfaces exposed to air and helium showed that the Ba content of Ba0.8Sr0.2Co0.8Fe0.2O3-delta makes the most oxygen permeation, while the Ba content of Ba0.2Sr0.8Co0.8Fe0.2O3-delta makes the highest stability.