Cr1-xAlxN coatings are known for superior mechanical and thermal properties, which make them promising candidates for advanced machining and high temperature applications. Their oxidation resistance can further be improved by alloying oxygen active elements such as yttrium, which promote growths of dense and adherent oxide scales. Based on x-ray diffraction and transmission electron microscopy studies the authors can conclude that our films with an Al/Cr ratio of similar to 1.2 exhibit a single phase NaCl-type crystal structure for the investigated Y-content variation. With increasing YN mole fraction from 0% to 8% the lattice parameter increases from similar to 4.11 to 4.18 angstrom the hardness increases from similar to 31 to 38 GPa, the indentation modulus decreases from similar to 497 to 488 GPa, and the residual biaxial compressive stresses decrease from similar to-1.6 to -0.6 GPa, respectively. The mean crystallite feature size is found to be in the range of 28-43 nm for the coatings investigated. (c) 2007 American Vacuum Society.