Plain carbon steel specimens were surface-treated mechanically and then chemically before applying high-density polyethylene (HDPE) coating. Pretreated specimens were coated with HDPE powder, both with and without a heat stabilizer (Irganox 1010), using a spray electrostatic technique. Effects of various variables, such as surface roughness, prephosphating treatment, addition of stabilizer, and the role of curing time and temperature were investigated. Mechanical and immersion tests were conducted to measure adhesion, ductility, and corrosion resistance of the coated specimens. Scanning electron microscopy and infrared spectroscopy were used to study the microstructure of produced coating and its interface with the substrate, as well as the possible chemical changes that occurred. The results obtained revealed that, pure HDPE can be coated on plain carbon steel with a good performance. It was further observed that an addition of 0.5 wt % of heat stabilizer to HDPE powder increases the performance of produced coating significantly. This was evidenced by the measurements of adhesion, ductility, and corrosion resistance in sulfuric acid, sodium hydroxide, ferric chloride, water, and salt spray, as well as scanning electron microscopic examinations and infrared spectra.