Boron carbon nitride (BCN) films were deposited on to silicon and sodium chloride substrates by dual cathode magnetron sputtering from graphite and boron targets. Rutherford back-scattering (RBS) analysis was performed to determine the composition of the films. The chemical structure of the films was characterised by Fourier transform infrared (FTIR) spectroscopy. The tribological behaviour of the films was also examined. RBS analysis indicated that the boron contents of the BCN films deposited with 100 W r.f. power to the boron target and from 10 to 100 W d.c. power to the graphite target were less than the detection limit of 5 at.%. Oxygen content was > 8 at.% in all the films, although oxygen was not deliberately introduced into the chamber during deposition, implying that oxygen gas and/or water vapour had reacted with the films after exposure to air. Absorption bands, associated with hexagonal-BN, cubic-BN, graphite-like sp2 carbon, nitrile or isocyanate groups, and -NH or -OH, were detected in the FTIR spectra of the BCN films. The BCN films deposited in pure nitrogen contained higher content of sp and sp2 carbon, and showed lower durability in friction tests.