Abstract: A film of a composite material is deposited by electropolymerization onto electrically conductive surface. A mixture comprising a monomer, a substance forming a dopant, a supporting electrolyte and a solvent is subjected to electrolysis in which the conductive surface to be coated is used as either cathode or anode. The cathode or anode is polarized to a potential between the electron transfer between the electrically conductive surface and the monomer. Prior to electrolysis, a solution is made from the mixture containing the substance forming a dopant either as anion, cation, molecule, and/or as undissociated complex.