A comparative study of chemical and enzymatic methods of aniline polymerization was carried out. Fungal laccase from Trametes hirsuta was used in the synthesis of polyaniline nanoparticles made with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS). Template polymerization of aniline was carried out in aqueous buffer. It was shown that the laccase had high long-term and operating stabilities under acidic condition favorable for synthesis of conducting polyaniline. UV-vis, FTIR spectroscopy, and cyclic voltammetry analysis are used for the characterization of the polyelectrolyte complexes of polyaniline and PAMPS. The incorporation of the polymeric acid in polyaniline has been demonstrated by atomic force microscopy. The size and morphology of the nanoparticles of the polyaniline PAMPS complexes depended on the method of the synthesis. A comparison of some physical and chemical properties of water dispersible conducting polyaniline-PAMPS was performed under production by enzymatic and chemical methods. It was found a difference in structures and some physicochemical properties of polyaniline colloids prepared by chemical and laccase-catalyzed methods. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 1544-1550, 2010