The growth and nucleation mechanism of poly(ortho-ethoxyaniline) (POEA) are investigated by cyclic voltammetry (CV) and potentiostatic technique. It was shown that growing of POEA is faster in sulphuric acid solution compared to phosphoric acid solution. Different rate trends were obtained with the increase of switching potential. From cyclic voltammograms, it is evident that the obtained polymer has a similar behaviour to the one reported for polyaniline, but there is a difference in position of current peaks, due to the electronic and steric effects of ethoxy-group. In presence of different anions, a different nucleation mechanism was obtained. In sulphuric acid solution nucleation proceeds through 3D instantaneous nucleation under diffusion control, and in phosphoric acid solution nucleation proceeds through 3D progressive nucleation under diffusion control. (c) 2006 Elsevier Ltd. All rights reserved.