The most significant anthropogenic greenhouse gas is CO 2, which arises mainly from use of fossil fuels. A new technique called Advanced Zero Emission Power Plant (AZEP) has been developed these years targeting CO 2 capture and storage (CCS). In AZEP concept, CO 2-diluted O 2 is used to combust the fossil fuels, which produces a concentrated CO 2 gas stream and thus enables efficient CO 2 capture. The O 2/CO 2 mixture, necessary for combustion, could be supplied by using CO 2 to transport the oxygen as separated by oxygen permeable membrane from the air. After combustion, the concentrated CO 2 is partly recycled to the membrane as sweep gas, and the rest is captured. Mixed Ionic and Electronic Conductor (MIEC) membrane is one of the most promising oxygen permeable membranes for AZEP. However, most of the MIEC materials, which usually have the oxygen deficient perovskite structure, are not stable in CO 2 containing atmosphere because of the reaction between CO 2 and the MIECs. In our work, we have found that the CO 2 tolerance of some MIEC materials can be greatly enhanced by increasing the oxygen partial pressure in CO 2 and the presence of oxygen can effectively protect the MIEC membranes. Inspired by this phenomenon, we have developed new concept of AZEP by adding certain amount of oxygen to the inlet of the separation unit to protect the membranes, following oxygen permeation measurements have shown that the protective effect of oxygen for the membranes is quite remarkable.