Nitrocarburization is a thermal chemical process in which the nitrogen and carbon atoms are diffused into the surface of the workpiece simultaneously at the temperature around the eutectoid point (565 degreesC) of Fe-C-N. It can be applied for improving the properties of the work such as wear and seizure resistance, fatigue strength and hardness. The purpose of the article is to find out an appropriate combination of atmosphere for improvement of wear resistance by plasma nitrocarburizing of 316L stainless steel at the treating temperature of 570 degreesC for extending the application of the material. A ring-on-disc wear resistance test was employed for evaluation of the nitrocarburized layers derived from various treatment conditions. The formation mechanism of the topography and the microstructure of the nitrocarburized surface were also investigated in this article. The results show that the best wear resistance layer about 70 mum could be obtained on condition that the specimens were nitrocarburized in the atmosphere of N-2/H-2 = 4/1 with 2% CH4 addition in pressure of 560 Pa at 570degreesC for about 5 h. (C) 2003 Elsevier B.V. All rights reserved.