In this paper the authors studied the influence of energy of implanted nitrogen ions N + on the value of the friction coefficient and wear of tool steel NC10. Measurements were performed for a wide energy range of ions: 60, 120 and (1000-2000)keV. At a high implantation energy changes of tribological properties in the surface layer up to 0.5μm thick were largely connected with defects. Annealing deeply implanted samples did not, as shown by CEMS measurements, lead to formation of nitrogen compounds in the surface layer =<0.1μm thick. It neither resulted in improvement of the tribological properties. The best results with regard to improved tribological properties were obtained at 120keV implantation energy.