Аннотация:The concept of charge transfer and its interpretation in the current literature are analyzed. The problem of partial charge transfer in adsorption phenomena is thermodynamically analyzed in the instance of the simplest reaction, of the type O plus e** minus reversible reaction R, which takes place via the two adsorption steps O plus n//1e** minus reversible reaction A and A plus n//2e** minus reversible reaction R. The physical significance of the quantities n//1 and n//2 and their connection with the partial charge transfer coefficient lambda in the theory of Lorenz and with the ″electrosorption valence″ in the theory of Vetter and Schultze are discussed. Expressions are obtained for the formal charge transfer coefficients during adsorption of a solution ion at a reversible electrode.