Cubic boron nitride (cBN) thick films deposited on mainly c-axis-oriented graphite substrate at room temperature and zero bias by radio frequency (RF) magnetron sputtering were studied. In the growth process, RF power plays a key role in determining the content of cubic phase in films, while the conventional substrate heating and biasing have been neglected. With increase in RF power, the dominated content of films converts from explosion boron nitride (eBN) to cBN. The transformation mechanism has been discussed. The unique structural properties of the "soft" graphite are favorable to propose simple conditions for growing "hard" cBN films. Furthermore, the optical band gap of BN films having similar to 90% cubic phase is of similar to 5.8eV obtained from ultraviolet-visible optical transmission measurement. The electron field emission examination shows that cBN film on graphite has a high emission current density of 2.8 X 10(-5) A/cm(2) at an applied field of similar to 30V/mu m. (C) 2009 Elsevier B.V. All rights reserved.