based on cobalt oxide thin film was carried out using the step potential excitation method. A method based on generating plots of current density as a function of passed charge has been applied for characterization of electrochromic cobalt oxide thin films using an aqueous KOH electrolyte. The device resistance and the intercalation capacity of the material are calculated. Dynamic built-in potential estimated from step potential experiment and plots of the built-in potential as function of the passed charge, V-bi(DeltaQ), are generated for intercalation process. The intercalation efficiency curve is obtained to confirm the nature of energy distribution of intercalation sites in electrochromic cobalt oxide.