The aniline electrochemical polymerization and its co-polymerization with oaminophenol on stainless steel (SS) and Nafion®-coated SS substrates is addressed in this paper. The cyclic potential sweep method (CPS) was used for the deposition of polyaniline (PAn) and copolymer films from monomer-containing 0.5 M H2SO4 solutions. Successive cyclic of the potential between -0.2 and 1.1 V results in copolymer films on both the bare SS and Nafion®-coated SS. The electrochemical response of copolymer films in monomerfree 0.5 M H2SO4 solutions exhibit different redox properties from those of PAn films. Scanning electron microscopy reveals also a more compact structure for the copolymer than the PAn film. The different redox behavior is due to the functional group –OH on the copolymer chain, which is associated with proton exchange resulting in an adjustment of the pH near the copolymer surface. Monitoring the open circuit potential of the copolymercoated SS electrodes versus time in comparison with that of PAn-coated electrodes indicates differences that may result in different corrosion protection properties. This is might be rationalized by considering different redox properties and thereby different structure of copolymer films. Keywords: Polyaniline; o-aminophenol; copolymer; Nafion-polymer composite films; Corrosion control