The adsorption of I- ions on the Cd(000 1) single crystal plane from solutions in ethanol has been investigated by impedance measurement method. The ionic charge due to the specific adsorption has been obtained using the mixed-electrolyte method for both electrode charge and electrode potential as the independent electrical variables. The Gibbs energy of adsorption of ions has been calculated using the different modifications of the virial adsorption isotherm. It was found that under comparable conditions the results obtained at constant electrode potential and at constant electrode charge are coincident and the adsorption of I- anion increases in the sequence of solvents: water < ethanol and metals: Cd < Bi. The electrosorption valency has been calculated. It was found that on the Cd(000 1) plane the electrosorption valency has a constant value that is similar to this value for Bi single crystal planes. (c) 2007 Elsevier B.V. All rights reserved.