The improvement of the adhesion of a coating film to the coated material and of its wear resistance is a fundamental aspect for protective hard coatings. As a consequence, the optimization of the deposition techniques is required to properly tune the film properties. Among the numerous materials for hard coatings, zirconium nitride (ZrN) is extensively studied for use in tribological applications, thanks to its high hardness, strong wear resistance, chemical stability and high corrosion resistance. In this work ZrN films were RF-sputtered on silicon and tungsten carbide substrates, with different assistance bias voltages applied to the substrate during the film deposition. Their adhesion and wear resistance properties were evaluated and correlated to the structural and compositional properties, showing the best responses (higher critical load and scratch hardness, and lower wear rate) when using a low negative bias voltage (-5 V). (c) 2012 Elsevier B.V. All rights reserved.