To increase the corrosion resistance of an iron substrate, conducting polymers were electrochemically synthesised from a solution containing 1,5-diaminonaphthalene and aniline. MIRFTIRS, AFM and electrochemical characterisation indicated the formation of a two layers composite polymer. The first layer, of poly(4,5-diaminonaphthalene) was compact, homogeneous, thin and adherent to the substrate and the top layer, of polyaniline, was thick and fibrous.