La2NiO4+d and its derivatives are considered by scientists as promising membranes for oxygen separation and cathode materials for intermediate-temperature solid oxide fuel cells. Therefore, a special attention is required, not only on their bulk properties but also for surface structure. This work is aimed to study the physicochemical properties and surface of polycrystal membranes La1.5Sr0.5Ni1-yMeyO4+d (Me = Co, Mn; y=0–0.4), in order to reveal the reason behind the surface limitations during the oxygen incorporation in the structure of these materials. The temperature dependencies of the following properties in La1.5Sr0.5Ni1-yMeyO4+d (Me = Co, Mn; y=0–0.4) will be studied: oxygen non-stoichiometry, total conductivity and the Seebeck coefficient. The concentration and mobility of the point defects participating in oxygen exchange processes between the material and gaseous phase will be calculated. The measurement of oxygen permeation flux through the La1.5Sr0.5Ni1-yMeyO4+d membranes with different thickness will let us determine the role of surface exchange and bulk diffusion in the total oxygen-ion transport and to calculate the values of oxygen diffusion and surface exchange coefficients. The surface of the studied membranes will be analyzed by scanning electron microscope equipped with a detector of backscattered electrons allowing us to determine the grains orientation, their shape and size. It is assumed that the obtained data could help to reveal the reason of surface exchange limitations in the oxygen-ion transport through the La2NiO4+d-based membranes.