In this work, the mediated reduction and oxidation of Fe(CN) 6 3-/4- and Fe 3+ in poly(o-aminophenol) coated electrodes is analyzed by means of diagnosis diagram based on the features of steady state current-potential curves. This analysis allows to identify the current determining process and to reproduce the experimental characteristics of the polarization curve from the relevant kinetic and thermodynamical parameters with a minimum amount of experimental measurements.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas