The electrochemical synthesis of polyaniline (PANI) layers was studied in mixed inorganic/organic acid solutions containing poly(2-acrylamido-2-methyl-1-propane-sulfonic) acid (PAMPSA) or the corresponding monomeric acid, AMPSA, under both potentiostatic and potentiodynamic conditions. Electrosynthesis in the presence of a small amount of PAMPSA in the mixed solutions resulted in accelerated polymerization in both growth modes whereas the AMPS anions slowed down the process. Scanning electron microscopic studies indicated a marked influence of the PAMPS and AMPS anions on the surface morphology of potentiostatically synthesized PANI. The electrochemical stability of PANI layers was studied by continuous potentiodynamic cycling. The PANI layers degradation behaviour was found to follow two different patterns depending on the mode of synthesis and not on the anions present in the polymerization solution. (C) 2009 Elsevier B.V. All rights reserved.