The electrochemical behaviour of electrodes modified with a Co/Al-NO3 hydrotalcite-like compound was investigated by voltammetric techniques and electrochemical impedance spectroscopy in aqueous solution. The latter technique was used in order to study the electronic and ionic transport, both inside and on the surface of the material. The behaviour of the modified electrode was studied at different OH-concentrations (pH 11- 12.8) and at different temperatures, with the aim to calculate the activation energies of the electronic conduction and charge-transfer processes. The electronic conductivity of the bulk material is dependent on the Col(III)/Co-II ratio and results the limiting parameter of the overall redox process. The same result was previously obtained for the Ni based hydrotalcite, but the latter material showed a better electrical conductivity. © 2004 Elsevier Ltd. All rights reserved.