The invention relates to a piston ring for internal combustion engines, the piston ring comprises a steel or cast iron base material with a coating of chromium nitride deposited by a physical vapor deposition process on a sliding surface of the piston ring, wherein the coating is composed of a columnar crystal structure of CrN with the following features: (a) an oxygen content in solid solution of 0.5 to 2.5 wt %; (b) a content of uniformly dispersed micro-pores of less than 10% in volume of the coating; and (c) an X-ray diffraction intensity ratio of (111) planes to (200) planes parallel to the surface in the range of 0.80 to 1.20.