In this work the electrochemical intercalation of oxygen in La2CuO4 phases has been studied. Oxygen intercalation has been performed at different anodic potentials for fixed time in alkaline solution (1 M NaOH) at room temperature. The electrochemis- try of the phenomena taking place at the oxide—solution interface has been investigated by cyclic voltammetry (CV), controlled- potential coulometry, and electrochemical impedance spectro- scopy (EIS). The homogeneity of processed samples and the lattice parameters prior to and after oxygen intercalation have been verified by X-ray powder diffraction. SEM has been used to relate surface modification to the potential applied after electro- chemical oxygen intercalation. The recent theories and know- ledge of mechanisms of oxygen intercalation into the oxide lattice have been related to the experimental results. Oxygen intercalation seems to occur at potentials slightly lower than that of the oxygen evolution reaction (OER) and proceeds on a paral- lel pathway to O2 evolution at more anodic potentials.