[en] Radiochemical measurements of adsorption on single crystal, well-defined electrodes are reported and the method of the measurements is described. Adsorption of acetic acid on Pt(111) surface was studied: the surface concentration data were correlated with voltammetric profiles of the Pt(111) electrode in perchloric acid electrolyte containing 0.5 mM of CH₃COOH. It is concluded that acetic acid adsorption is associative and occurs without a significant charge transfer across the interface. Instead, the recorded currents are due to adsorption/desorption processes of hydrogen, processes which are much better resolved on Pt(111) than on polycrystalline platinum. A classification of adsorption processes on catalytic electrodes and atmospheric methods of preparation of single crystal electrodes are discussed