Nickel-Phosphorus electroless coatings (deposition without electric current) have been considered by artisans and researchers for a long time due to the suitable corrosion and wear resistance. In many environments, corrosion and wear simultaneously cause failure of materials due to the combination of electrochemical, chemical and mechanical (known as tribocorrosion ) Phenomena. Therefore the goal of this project was to evaluate the tribocrrosion of Ni-P electroless coating (in medium Phosphorus state) in three conditions (without heat treatment, heat treated at 400 and 600 ). To do this, uniform, hard and corrosion resistant coatings of Nickel with about 9 %wt. of Phosphorus had been coated on CK45. The formed coating without heat treatment was consisted of amorphous and crystalline structures. Formation of a rich layer of Phosphorus prevents the nickel dissolution by formation of a diffusion barrier. While after heat treatment, the coating completely became crystalline and a thin layer of nickel-oxide was formed on the coating. For each three coatings, cyclic polarization curves showed the passive zone due to the formation of surface protective layers. Because of the nature of passive layers, the coating without heat treatment provided better protection. According to tribocrrosion tests and conducted calculations in the basis of ASTM G119 standard, the coating without heat treatment (as plate) showed the maximum mass loss and HT400 sample showed the minimum mass loss due to its higher hardness. While the current density-time diagrams indicated that HT400 coating showed an increase in current density during and after sliding. This indicates that the sliding plays more important role than corrosion in tribocorrosion test. Keywords : Elecrroless coating, Nickel-Phosphorus, Tribocorrosion, Heat treatment