A novel dual phase composite oxygen transport membrane (Al0.02Ga0.02Zn0.96O1.02-Gd0.1Ce0.9O1.95-δ) was successfully prepared and tested. This membrane shows chemical stability against CO2 and SO2, and stable oxygen permeation over 300 hours in CO2 was demonstrated. ZnO is cheap and non-toxic and is therefore highly advantageous compared to other common materials used for this purpose.