Perovskite oxide, La0.4Ba0.6FeO3-delta (LBF), is a typical cobalt-free, mixed ionic-electronic conductor. This work explored B-site doping in LBF by partially substituting iron with Zn, which results in La0.4Ba0.6Fe1-xZnxO3-delta (LBFZx). An investigation on the effects of Zn doping was then conducted. The introduction of Zn in LBFZx largely augments the concentration of oxygen lattice vacancies and the chemical resistance against reduction in the H-2(5%)/N-2 atmosphere. This conclusion was drawn from the results of X-ray diffraction and temperature-programmed reduction. Furthermore, the O-2 temperature-programmed desorption showed us that lattice oxygen desorption is affected by the vacancy concentration and the amount of movable lattice oxygen. The oxygen permeability of the LBFZx membrane increased from 800 to 950 degrees C, with increasing Zn2+-doping extent (x-value) from 0 to 0.1, but the improvement discontinued with further increase in the x value from 0.1 to 0.2, namely both LBFZx (x = 0.1 and 0.2) membranes presented the same oxygen permeation flux as high as 0.73 mL cm(-2) min(-1) at 950 degrees C. Nevertheless, perovskite LBFZx with x = 0.2 exhibited superior chemical stability in reducing atmosphere at 900 degrees C over that with x = 0.1. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3454212] All rights reserved.