The evolution of the electric properties of Nb₂O₅, Ta₂O₅ and WO3 films, at different formation potentials (Ef), in 0.1M HClO4 and 0.1M KOH, were followed with electrochemical impedance spectroscopy (EIS). During the potentiostatic growth, the EIS spectra were acquired every hour, maintaining the potentiostatic pulse during 20h. Nb₂O₅ , Ta₂O₅...