Polyaniline (PANI) coatings were electrochemically synthesized on nickel (Ni) coated mild steel (MS) and their corrosion protection properties were investigated. In this work, the Ni layer (similar to 1 mu m thick) was electrodeposited on MS under galvanostatic condition. Thereafter, the PANI coating was deposited over the Ni layer from aqueous salicylate medium by using cyclic voltammetry. These bi-layered composite coatings were characterized by cyclic voltammetry, UV-vis absorption spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The corrosion protection properties of Ni coated MS (Ni/MS) and PANI coated Ni/MS (PANI/Ni/MS) were investigated in aqueous 3% NaCl by using open circuit potential (OCP) measurements, potentiodynamic polarization technique and electrochemical impedance spectroscopy (EIS). It was shown that the top layer of PANI exhibits a lower porosity behavior with respect to Ni coating and reduces the corrosion rate of Ni/MS almost by a factor of 3500 and increases the lifetime of Ni coating. (C) 2011 Elsevier Ltd. All rights reserved.