LSM/ScCeSZ nanocomposite was prepared via ultrasonic dispersion of the mixture of perovskite and fluorite powders in isopropanol in 1:1 ratio with addition of polyvinyl butyral. Studies of the real structure and surface property evolution at sintering under air up to 1100 degrees C revealed some redistribution of elements between the phases without new phase formation. Sizes of both phase domains remain in nanorange even in the dense material, thus providing a developed perovskite-fluorite interface. The surface layer of nanocomposite is enriched by LSM. The oxygen mobility and reactivity estimated by the oxygen isotope exchange and O-2 TPD exceed those for LSM suggesting a positive role of interfaces as fast oxygen migration paths. Button-cell tests with the LSM/ScCeSZ interlayer between LSNF and a thin ScYSZ layer covering Ni/YSZ cermet demonstrated a high and stable performance promising practical application promising for practical application. (C) 2010 Elsevier B.V. All rights reserved.