BaCe0.1Co0.4Fe0.5O3-delta, a new mixed ionic-electronic conducting (MIEC) perovskite oxide, was successfully synthesized, which has high oxygen permeability and excellent structural stability. Through the XRD characterization, it was shown that only if the amount of cobalt is no more than 40%, pure perovskite phase can be obtained. Oxygen permeation flux of BaCe0.1Co0.4Fe0.5O3-delta permeable membrane reaches at 1.35 ml min(-1) cm(-2) at 950 degrees C with membrane thickness of 1 mm. In oxygen permeation operation of 270 h at 800 degrees C and 750 degrees C, no degradation of oxygen permeation flux was found. An increasing process was observed in the initial oxygen permeation of BaCe0.1Co0.4Fe0.5O3-delta which took about 40 h to reach steady state. If the thickness of the membrane is thicker than 0.7 mm, bulk diffusion is the rate-determining step of oxygen permeation. And if its thickness is thinner than 0.7 mm, oxygen permeation process is mainly controlled by surface exchange mechanism. (C) 2009 Elsevier B.V. All rights reserved.