A plasma-nitriding system was built by plans of professor Blücher at the BME Department of Materials Science and Engineering. The aim of this surface treatment equipment is to produce nitrided layers on different steels. The aim of our research work is to analyze with SEM-EDS and XRD the surface of tempered steel after plasma-nitriding. We made specimens in our laboratory and, for comparing, at an industrial partner in its equipment. Metallographic and hardness testing and microstructural characterization were performed.