Nanocrystalline chromium nitride (CrN) was synthesized via a simple thermal decomposition–nitridation route by the reaction of ammonium dichromate and Mg powders in an autoclave at 550 °C. X-ray powder diffraction pattern indicated that the product was cubic CrN, and the cell constant was a = 4.146 Å. Scanning electron microscopy image showed that it consisted of uniform particles with an average size of about 25 nm. The product was also studied by BET.