A long-term study of Cu UPD and OPD kinetics on the Pt(111) electrode by cyclic voltammetry and potentiostatic current transient techniques has shown that copper oxides CuxO could be considered as the active centers of the adlayer growth and further bulk copper deposition. These species are formed by a slow surface reaction between the adsorbed oxygen and copper atoms or ions at potentials E > 0.55 V versus NHE. An enhanced rate of copper cations reduction on the positively charged Pt surface in the vicinity of electronegative CuxO species caused by the local electrostatic effects in the electric double layer could be the reason for the accelerating action of these active centers.