The nucleation and growth mechanisms of polyfurane films doped with perchlorate anions (PFu/ClO4) were investigated on platinum electrodes in acetonitrile media. From the chronoamperometric response two different stages were distinguished, depending on applied overpotential and concentration conditions. At short times (t < t(o)) the nucleation of the new phase was related to a diffusion-controlled process, and at longer times (t > t(o)) the current was due to a mixture of progressive and instantaneous nucleation of small hemispherical nodules controlled by spherical diffusion. Three-dimensional growth was found. (C) 2000 Elsevier Science Ltd. All rights reserved.