Nanocrystalline TaB2 has been prepared via a simple inorganic solvent thermal route by the reaction of metallic magnesium powders with tantalum pentoxide and boric acid in an autoclave at 650 degrees C. X-ray powder diffraction patterns indicate that the product was hexagonal tantalum diboride. Scanning electron microscopy images show that it consisted of particles with an average size of about 40 nm. The product was also studied by BET and TGA.