Boron nitride (BN) nanometer films are synthesized on Si(1 0 0) substrates by RF reactive magnetron sputtering. The surfaces of BN films are treated with hydrogen and oxygen plasma, respectively and studied by Fourier transform infrared (FTIR) spectra. atomic force microscopic (AFM) and field emission characteristics. The results show that the surface negative electron affinity (NEA) of the films is increased, the threshold field reduced and the emission current increased due to hydrogen plasma treatment. The effect of oxygen plasma treatment on field emission characteristics of BN films is obscure. The result shows that only the emission current is slightly decreased due to the surface oxidation of BN films. (C) 2004 Elsevier B.V. All rights reserved.