AbstractPolyaniline films have been grown in solutions based on acetonitrile or acetonitrile/nitromethane mixtures by galvanostatic, potentiostatic and cyclic voltammetry techniques. LiClO4 or anilinium tetrafluoborate was used as a salt. With the latter, aniline was absent in some tests, since anilinium could act simultaneously as a charge carrier and a polymerising species. The film characteristics have been evaluated by cyclic voltammetry, impedance spectroscopy and SEM experiments. It has been found that the protons released by aniline (following oxidation) or anilinium can be made available to the g| wing chains if the protophilic character of the solvent is sufficiently low. In a 1/1 acetonitrile/nitromethane mixture the galvanostatic and potentiostatic techniques produce electroactive films of reduced resistance, especially if anilinium tetrafluoborate is present. These seem to be the best conditions for the synthesis.