A thermodynamic analysis of charge density data was performed to describe chloride adsorption at the Au(lll) electrode surface. The Gibbs excess, the Gibbs energy of adsorption, the number of electrons flowing to the interface per adsorbed chloride ion at a constant potential (electrosorption valency) and a constant chloride concentration (reciprocal of the Esin-Markov coefficient), and the dipole formed by adsorbed ion and its image charge in the metal were determined. Chloride forms a chemisorption bond with gold whose polarity is a strong function of the charge on the metal. The bond is fairly polar at the negatively charged surface; however its polarity drops significantly at positive charges. The adsorption behavior of this anion is asymmetric with respect to the charge on the metal.