Poly(5-amino-1-naphthol) is a new conducting polymer, obtained by electropolymerization of 5-amino-1-naphthol. Raman spectroscopy confirms the structure which consists of amine (-NH-C) and imine (-N=C) links between naphthalene rings, characteristic of a polyaniline-like structure. Its redox properties were investigated in aqueous acid (pH 0) by in situ Raman spectroscopy. Some amine units are reversibly transformed into imine groups on oxidation.