The major topic of this work is a thorough investigation of the thermal stability as well as the oxidation resistance of PVD-AlCrN coatings. These properties are determined by diffusion processes. Due to the complex interaction in oxidative atmosphere, a first attempt was taken to determine decomposition processes during heat treatment in inert gas atmosphere, and the so formed phases. Heat treatment of samples in oxidative atmosphere was done to identify the influence of the chemical composition on the oxidation resistance, oxide phase formation and interdiffusion processes. In addition, focus was set on the mechanical properties of the coatings. Hardness after heat treatment in inert gas atmosphere and abrasive wear resistance at ele-vated temperatures depending on the chemical composition were examined. The adhesive wear behaviour in contact with austenitic stainless steel was studied for the as deposited films as well as after post deposition polishing. These basic results on structure-property relations are supported by two industrial application tests. A drilling test delivers quick information about the coating performance. More detailed tapping tests of AlCrN and for comparison other PVD coatings against austenitic stainless steel are also done. Here, the link between coating performance, mechanical properties and coating structure is given.