Wear rates of nickel-fly ash composite coatings on mild steel have been measured for unlubricated rubbing against a rotating hardened steel disc. Wear losses of composite coatings were lower than those of nickel coating. The higher wear resistance of the composites may be attributed to the presence of fly ash, the excellent bonding between particles and matrix and the smearing-out of fly ash on both counterdisc and specimen. Optical and scanning electron microscopical investigations of the tested specimens were also carried out. © 1991.