Conducting polyaniline (PANI) is being explored as promising material for protection of metals against corrosion. It has the possibility of making smart coatings on metals, which can prevent corrosion even in scratched areas where bare metal surface is exposed to the aggressive environment. However, PANI coatings have poor barrier and mechanical properties. The barrier property of coatings can be enhanced by the addition of appropriate filler particles. Also it has been demonstrated that nanoparticulate fillers give much better barrier properties even at lower concentrations. In this study, the effect of zinc nanoparticles on the anticorrosive property of PANI coating on iron samples has been investigated. The PANI/Zn nanocomposite was synthesized by in situ polymerization of aniline in the presence of Zn nanoparticles. The nanocomposite was characterized by using FTIR, conductivity measurement, cyclic voltammetry, and AFM techniques. Results showed that PANI/Zn nanocomposite coating has improved corrosion protection effect when compared with pure PANI coating. The corrosion current of PANI/Zn coated samples were found to be much lower than that of pure PANI coated samples. The results were referred to the good barrier properties of Zn nanoparticles and improvement in electrochemical corrosion protection of PANI coating in the presence of Zn nanoparticles. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 2221-2227, 2010