In this study, the wear behavior of plasma nitrocarburized AISI 4140 steel at different treatment temperatures was investigated. Plasma nitrocarburizing was carried out at 530°C, 570°C and 630°C for 5h in an atmosphere of 80vol.% N 2 , 17vol.% H 2 and 3vol.% CO 2 . The treated samples were characterized using XRD, SEM, roughness and microhardness techniques. The wear behavior of the treated samples was studied by pin-on-disk method. The results confirmed formation of ε and γ´ phases in compound layer in all treatment temperatures. The amount of ε phase increased as the treatment temperature rose from 530°C to 570°C and decreased at 630°C. Nitrocarburizing at 570°C demonstrated the highest surface hardness, highest wear resistance and lowest friction coefficient among all treatment conditions.