We report the electropolymerization and characterization of polyaniline (PAN) on both DNA monolayer and single poly(dG)-poly(dC) DNA molecules serving as a template. The synthesis includes the formation of an electrostatic complex between the negatively charged DNA and positively charged anilinium ions followed by electrochemical oxidation and polymerization of the anilinium ions' monomers on the DNA template. The polymerization was carried out on a flame annealed gold substrate modified with positively charged self-assembled 4-aminothiophenol (4-ATPh) monolayer. The resulting monolayers and single macromolecular composites of DNA-PAN were characterized by atomic force microscopy (AFM), cyclic voltammetry (CV) impedance and UV-vis spectroscopy. (C) 2008 Elsevier Ltd. All rights reserved.