Poly(o-methoxyaniline) was chemically prepared in the presence of hydrochloric, p-toluene-sulfonic, dodecyl-benzene-sulfonic or dodecyl-sulfuric acids. Films of this polymer were prepared by casting and electrochemical, electrochromic and photoelectrochemical properties were studied. Cyclic voltammetry experiments show well-defined redox waves when the pH of the electrolyte is 1.0. Poly(o-methoxyaniline) films present high optical contrast in the visible range, when the potential is changed from the fully reduced to the fully oxidized state, independently of the dopant acid, The film obtained from the polymer doped with p-toluene-sulfonic acid, however, presents the highest contrast. Photoelectrochemical experiments also showed that this material yields photocurrent when irradiated with monochromatic light (330 nm), and that the sign of the photocurrent depends on its oxidation state.