tIn this study, polyaniline (PANI) and polyaniline/clay nanocomposites were prepared via in situ oxida-tive polymerization. The morphology of nanocomposites structures was investigated by X-ray diffraction(XRD). The chemical structures of PANI and PANI/clay nanocomposites were examined via Fourier trans-form infrared (FT-IR) spectroscopy. Polyaniline-based pigments were introduced into epoxy paint andapplied on steel substrates. The effect of clay addition and the type of clay cation, including Na+innatural clay (MMT) and alkyl ammonium ions in organo-modified montmorillonite (OMMT), on theanticorrosion performance of epoxy-based coatings was investigated through electrochemical Tafel test,electrochemical impedance spectroscopy and immersion measurements in NaCl solution. The stabilityof the adhesion of the neat and modified epoxy coatings to the steel surface was also examined. Theresults indicated that introduction of PANI/OMMT nanocomposite into epoxy paint results in improvedanticorrosion properties in comparison with PANI/MMT and neat PANI.