Corrosion of metals leads to high maintenance costs as well as potential threats to structural health and safety. Here we demonstrate the coating of cobalt tungstate (CoWO₄) nanoparticles (NPS) / 5-mercapto-1-phenyl-1 H-tetrazole derivative (MPT) as a nanocomposite film on Cu surface for the blocking of micropores to hinder the propagation of metastable pits in an aggressive NaCl medium. The mechanism of interaction between the nanoparticles and tetrazole derivative, in addition to the mode of anchoring and blocking of penetration are all investigated. In this experiment, CoWO₄ was synthesized via a wet chemical route and thereafter, was combined with MPT at an optimized ratio thus formulating a nanocomposite corrosion inhibitor. Atomic force and Scanning electron microscopic images of the bare Cu reveal dip pits which by the coating of the nanocomposite were suppressed at the nucleation stage during exposure to the aggressive 3.5% NaCl electrolyte under flow condition. Electrochemical analysis shows high protection of Cu up to 97% efficiency in the presence of the newly formulated nanocomposite inhibitor film.