ABSTRACT A Ni–W alloy coating with a thickness of 5 μm was electroplated on N80 steel, and its electrochemical performance in a 3.5% NaCl solution was investigated. The atomic models of passive films and corrosion mechanism were analysed with the density functional theory calculation. The results show that the electroplated Ni–W alloy coating is composed of W atoms in the Ni lattice, and its surface roughness and particle size are 66.1 and 640.4 nm, respectively. The corrosion current density of Ni–W coating is lower than that of the substrate, indicating better corrosion resistance, while the corrosion potential is opposite, which is more passive than the substrate. The total impedance of Ni–W coating is higher than that of the substrate, which is attributed to the formation of NiO passive film during the corrosion process.