Boron nitride thin films were prepared on Si(100) substrate by CVD. Triethylboron and ammonia were employed as precursors and various operating parameters such as reactor pressure, temperature, feed rates of gases were varied to investigate their effects on deposition rate and film characteristics. Total gas pressure in the reactor was varied from atmospheric to I torr. Deposition temperature was in the range 850 – 1,050 °C. Deposition rate increased with partial pressure of TEB but decreased with total pressure in the reactor. Deposited films were examined with SEM, FTIR, XPS, AES, XRD. Prepared films were BN of turbostratic structure.