The in situ atomic force microscopy and the electrochemical studies on electropolymerization of the o-methoxyaniline in the 0.0-0.8 V versus NHE range of the electrode potential are described. It is proved that in the 0.0-0.3 V versus NHE a redox process takes place, resulting in the formation of poly(o-methoxyaniline) in its reduced form, leucoemeraldine. The different morphologies are exhibited by poly(o-methoxyaniline) under different polymerization conditions. The microscopic results show that with the increase of the monomer concentration in the bulk of electrolyte solution the globular morphology, related to the coil like molecular structure, is replaced by the fibrilar one, related to the opened-up, more conductive extended coil structure. It is shown that oxidation of a leucoemeraldine state of polymer to its emeraldine state results in the change of the morphology from the chain like structure to the massive fibrilar like structure. The reduction of oxidized polymer results in its irreversible fragmentation. (C) 2005 Elsevier Ltd. All rights reserved.