HfN/Si 3 N 4 and NbN/Si 3 N 4 multilayer coatings are deposited onto a high speed tool steel substrate by reactive sputtering. Their mechanical properties are evaluated in terms of the dependence of hardness and adhesion strength on the sputter deposition process parameters. X-ray photoelectron spectroscopy analyses were performed to analyze the chemical states of the coatings. The hardness of both HfN/Si 3 N 4 and NbN/Si 3 N 4 multilayer coatings increase as the N 2 /Ar flux ratio increases up to 0.4 and then remain unchanged. The hardness of both multilayer coatings nearly do not change with annealing at low temperatures, but decrease at high temperatures over 800 o C because of oxidation. Post-annealing at low temperatures increases the adhesion strength of the multilayers, but high temperature annealing does not.