The corrosion resistance of mild steel, used to make hull plates in ship technology, in sea water before paint coating [Nippon paint SUMO XTRA durable exterior emulsion coating (emulsion coating)] and after paint coating has been measured by electrochemical studies such as polarisation study and AC impedance spectra. It is observed that after paint coating, the corrosion resistance of mild steel hull plates increases. Polarization study reveals that after paint coating, the linear polarization resistance increases and corrosion current decrease. AC impedance spectra reveal that in the presence of paint coating charge transfer resistance value increases, impedance value increases, phase angle increases and double layer capacitance value decreases. The corrosion inhibition efficiency was greater than 99%. The hull plates made of mild steel may be coated with durable exterior emulsion coating (emulsion coating). This will control the corrosion of the hull plates in the sea water. There will be increase in the life time of the hull plates.