Electropolymerization of 1,5-diaminonaphthalene (1,5-DAN) in acetonitrile solution was studied using cyclic voltammetry and a rotating disc electrode. The poly(1,5-DAN) is electroactive in acetonitrile solution and aqueous solutions at pH < 4. The apparent diffusion coefficient was determined for polymeric films by using potential-step chronoamperometry. In situ Raman and ex situ IR spectra were recorded to determine the molecular structure of the polymer. The resonance Raman spectrum dependent on electrode potential reveals the electrochromic properties of the polymer. The IR and Raman results are discussed in terms of the possible molecular structure of the polymer units.