Since there are many difficulties in the preparation of supported oxygen-selective perovskite dense membranes on porous supports due to the problem of compatibility between the deposited membrane and the support material, one strategy to alleviate the problem is to fabricate mesoporous perovskite membranes on porous supports before deposition of a dense top layer with similar or adapted composition. In this study, the supported mesoporous membranes of La0.2Sr0.8Co0.8Fe0.2O3-delta (LSCF) without defect were prepared on porous surface-modified alumina supports using Pechini-type polymeric precursors by the dip-coating method. The LSCF polymeric precursor and the supported LSCF membrane were characterized by means of thermogravimetric analysis (TGA), X-ray diffraction (XRD), scanning electron microscopy (SEM) and liquid-liquid displacement porometry (LLDP). It is found that the membranes prepared are of orthorhombic perovskite phase, and the twice dip-coated membrane determined by SEM and LLDP is crack-free and about 0.7 mu m in thickness, with an average pore diameter of 5 nm.