The electrodeposition of polyaniline (PANI) was carried out in potentiostatic, galvanostatic and potential sweep regimes in the presence of water-soluble polymeric sulfonic acids with different structure. The course of polymerization was traced by chronoamperometry, chronopotentiometry, cyclic voltammetry and in situ AFM measurements. The rigidity of the polyacid backbone, the distance between sulfonic groups on the backbone, the length and rigidity of the side chains containing sulfonic groups were shown to affect the onset potential of aniline oxidation, the character and the rate of the initial stages of PANI/polyacid film growth. AFM data indicated that the structure of the polyacids has a direct influence on the shape of PAN! "nuclei" and the morphology of the film in the early stages of the electropolymerization. The obtained films were characterized by UV-Vis-NIR spectroscopy and cyclic voltammetry. (C) 2013 Elsevier Ltd. All rights reserved.