AbstractTitanium carbonitride and titanium nitride coatings deposited on two powder metallurgy high speed steels have been characterised with respect to their microstructure, residual stresses, thickness, and hardness. The adhesion between coatings and substrates has also been determined. Finally, the tribological performance of the coatings was studied using an erosive wear test. The results show that the Ti(C,N) coating on the ASP 60 substrate is not only the hardest and best adhering, but also the coating with the lowest erosion rate. It is concluded that in order to obtain a general characterisation of the tribological properties of a coated material a number of coating properties must be determined. The overall performance of a coated component depends on both substrate and coating materials as well as their compatibility, and in order to fully understand how the substrate material influences the coating properties, powerful analytical techniques such as analytical transmission electron microscopy must be used.