Atmospheric pressure chemical vapour deposition (APCVD) of niobium selenide films on glass substrates was achieved by reaction of di-tert-butyl selenide with NbCl 5 at 250-600°C. X-ray diffraction showed that the NbSe 2 films were crystalline and of the 2H a poly-type with cell constants close to those expected (a = 3.44 Å; c = 12.58 Å). Marked preferred orientation along either (101) or (200) was noted at higher deposition temperature and this unexpectedly varied depending on distance from the reactor inlet. The films produced at 600°C showed exactly the Nb/Se ratio expected for NbSe 2 by energy dispersive analysis by X-rays. The films