Nanocrystalline titanium oxynitride has been synthesized by a thermal liquid-solid metathesis reaction between TiCl4 and NaN3 at 350 degreesC. XRD shows the product is TiN0.91O0.09 with a NaCl-type structure (a = 4.236 Angstrom). TEM reveals the product is granular nanocrystals with size of 15-35 nm. XPS measurements indicate that the product is titanium oxynitride rather than titanium nitride. The photoluminescence spectra of the as-prepared nanocrystallites show the ultraviolet light emission at about 330-350 nm, which is reported for the first time. (C) 2003 Elsevier B.V. All rights reserved.