This paper was concerned with commercial pure iron plasma nitride at different bias voltages by high frequency and low voltage plasma nitriding. The results showed that the microstructure of the nitride layers was strongly influenced by the bias voltages. Compared with -1.5 kV and -2.5 kV, the pure iron plasma nitriding at -3.5 kV has the best wear resistance and corrosion resistance and its microhardness was three times than that of the virgin pure iron. The increase of bias voltage would promote the fort-nation of the nitride layers. The nitride layer which is composed of epsiv-Fe2-3N iron nitride and gamma-Fe4N iron nitride was a key factor in the properties enhancement of the commercial pure iron, which was modified by high frequency and low voltage plasma nitriding. (C) 2008 Elsevier B.V. All rights reserved.