The aim of this work is to analyse voltammetric and impedance behavior of the hydrated Ir oxide film grown on Ir by 10 Hz potential pulsing in 0.5 mol dm(-3) H2SO4 (AIROF), The solid-solution type Ir(+III)/Ir(+IV) redox reaction has been manifested in two-peak cyclic voltammograms both in 0.5 mol dm(-3) H2SO4 and 1 mol dm(-3) NaOH solutions, but with different reversibility. In order to elucidate the high charge storage capability of the oxidized Ir oxide film and to separate of the bulk and interfacial processes a structural analysis of electrochemical impedance diagrams was carried out in terms of bulk proton hopping coupled to electron transfer and electrolytic migration-diffusion and different acidic dissociation of the redox couple.