Steels provided with boronized diffusion coatings are known to exhibit excellent wear resistance at low sliding speeds. However, the sliding wear behaviour of boronized coatings at high sliding speed is not known. In the present study, the high speed sliding wear and friction behaviour of a boronized medium carbon steel has been characterized using a friction dynamometer. The boronized samples were tested against a hardened tool steel disc. The sliding tests were carried out at velocities up to 8 m s-1 and normal loads up to 2 MPa. These tests indicated that the wear rate of the steel can be reduced by about an order of magnitude as a result of boronizing. The coefficient of friction of the boronized steel was higher than that of the unboronized steels especially at higher sliding speeds. © 1995.