Diamond-like Carbon (DLC) coatings of thickness 3 μm and 10 μm were deposited with and without radical nitriding on stainless steel disk and ring specimens. Plasma CVD method was used to deposit the DLC coatings with silicon as dopant. The specimens were tested in vacuum under sliding contact condition to evaluate the tribological characteristics with reference to the DLC coating thickness and sliding distance. The results revealed that wear resistance was more for the highest coating thickness. The changes on the worn surfaces were observed and wear mechanism is discussed using ex situ analysis.