A polymeric sol–gel process was developed to fabricate porous thin layers of the perovskite-type La0.3Sr0.7CoO3–δ for membrane applications. A spin-coating technique was used for deposition of the layer on porous α-and γ-Al2O3 supports. Both supported and non-supported membranes were characterized by means of thermal analysis, X-ray powder diffraction, particle size analysis, scanning electron microscopy and permporometry. The main phase formed upon heating in air above 400 °C is cubic perovskite, although traces of SrCO3 and of an unknown phase can be observed up to 800 °C. Above this temperature, strong chemical interaction occurs between the deposited perovskite layer and the support material. The effects of the sintering temperature and the type of the La-precursor on the pore-size distribution were investigated.