In the present work, we review the occurrence of capacitive currents in conducting polymer and, particularly, in the electrochemical response of polyaniline film-coated electrodes Firstly, we present and discuss the differences between the electrical double-layer capacitance and the so-called pseudocapacitance. Then, we discuss the capacitive behavior of Pani as studied by a variety of electrochemical (cyclic voltammetry, electrochemical impedance spectroscopy) and spectroscopic techniques (epr, UV-visible). Understanding the capacitive behavior of polyaniline (Pani) becomes essential not only from an academic point-of-view but also from a technological perspective, as Pani has been extensively employed for the construction of materials for supercapacitors.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas