Present work investigates the wear resistance of SAE 52100 steel coated with nanocoating Al2O3 by the Metal-organic Chemical Vapor Deposition (MOCVD) process. The wear tests by sliding and abrasion were performed in a ball-on-disc apparatus whose ball substrate was SAE 52100 steel. The MOCVD nanocoating processes were carried out in a research laboratory apparatus at 240oC under N2 + O2+ H2O atmosphere. The counterface discs were ABNT 1008 steel sheet used in the Brazilian fridge industry. The wear resistance of the nanocoated steel spheres were evaluated through the ball-on-disc test, using a sliding velocity 0.6 m/s, normal loads of 20 N and 30 N, total sliding distance up to 2400 m and controlled conditions of temperature and humidity at 25oC and 42% respectively. The balls material substrates were submitted to two distinct coating procedures: direct Al2O3 film deposition on substrate, or phosphatizing and then Al2O3 deposition via MOCVD. The discs were tested as received. From the plotted graphs of cumulative lost volume versus sliding distance, lower wear rates were observed for the nanocoated SAE 52100 sphere compared to the sphere without coating, i.e., nanocoating with Al2O3 increases the sphere wear resistance. This is probably due to a reasonable film adhesion. The balls phosphatized and coated with Al2O3 showed similar wear resistance but a spherical micro-grain film of Al2O3 . The wear mechanisms were also examined by scanning electron microscopy.