The statistical mechanical approach in studying multilayer adsorption phenomena presented in the J. Phys. Chem., 100 (1996) 15247, is extended to electrified interfaces. According to this approach, an adsorbed him composed of solvent and adsorbate molecules forming n layers is mathematically equivalent to a monolayer of n + 1 components; which are the solvent molecules and columns of i (=1, 2,..., n) adsorbate molecules. The contribution of the field-dipole interactions to the chemical potentials is calculated by assuming that the electric field is not uniform across the adsorbed layer and all the other contributions, coming from the distribution of the adsorbed particles over the adsorption sites and from the particle-particle and particle-adsorbent interactions, are calculated using lattice statistics. It is shown that the model developed can predict, at least qualitatively, the adsorption characteristics of n-heptanol, n-hexanol, n-heptanoic acid and n-hexanoic acid on Hg when they form polylayers, the peculiar behaviour characterised by the appearance of just one transition potential at certain adsorption systems, like the adsorption of methyl- and dimethylpyridines on Hg, and finally the appearance of a transition pit inside another pit at the capacitance plots, observed in several experimental systems with ionic molecules or molecules of biological importance.