The objective of this work was to deactivate poly(o-aminophenol) (POAP) films and then study how their permeation and electron-transport processes are modified by the degree of deactivation. POAP films were deactivated by soaking in a ferric cation solution. The degree of deactivation (theta(c)) was assessed by employing Cyclic Voltammetry within the potential region where POAP exhibits its maximal electroactivity (-0.2 V < E < 0.5 V vs. SCE). Rotating Disc Electrode Voltammetry (RDEV) and ac impedance measurements were applied in the interesting case where POAP films contact a redox active solution containing the p-benzoquinone/hydroquinone redox couple and a mediation reaction occurs at the polymer vertical bar electrolyte interface. RDEV applied at potential values E < 0.0 V vs. SCE allowed obtaining a diffusion coefficient value, D(e). It was observed that D(e), decreases with increasing theta(c). This effect was attributed to the existence of inactive gaps within the redox site configuration of a deactivated film, which causes an increase in the hopping distance for electron conduction. The existence of inactive gaps seems to be related to the hindrance to accept protons by some redox sites in a deactivated film. This fact was proved by increasing the pH of the external solution contacting a non-deactivated POAP film. Impedance diagrams of deactivated films show an increase in the charge-transfer resistance at the metal vertical bar polymer interface. which is consistent with the presence of inactive zones within the redox site distribution of a deactivated film. Some deactivated POAP films were reactivated by treatment with an ammonium solution and it was observed that electron conduction can only be partially recovered. The permeation process at potential values where hydroquinone is able to diffuse through POAP was also analyzed on deactivated films. It was found that the rate of diffusion of hydroquinone decreases as the degree of deactivation increases. This effect was attributed to unfavourable partition equilibrium at the polymer vertical bar solution interface for the electroactive species in a deactivated film, as compared with a non-deactivated film. This work could be interesting due to the wide range of practical applications of POAP recently reported. In this sense, although in practical applications of POAP it is necessary to maintain its conducting properties unaltered, the polymer is subjected to extreme conditions that can cause its partial deactivation. Thus, it seems to be important to know at least how the charge-transport process changes at POAP films with their deactivation. (C) 2009 Elsevier B.V. All rights reserved.