This paper considers the mechanism of oxygen interaction with the surface of oxide electrode materials, such as LSM, and surface related electrical properties. The mechanism involves rapid oxygen chemisorption, resulting in an increase of the surface charge, followed by a slow oxygen incorporation, resulting in a shift of chemisorption equilibria and leading, in consequence, to a decrease of the surface charge. The latter process, involving transient chemisorption, is controlled by chemical diffusion. A good agreement between the chemical diffusion coefficient determined from work function and that determined by the manometric is revealed.