Nanocrystalline NbB2 powders were successfully prepared by borothermal reduction in molten salt at 800 degrees C-1000 degrees C. Due to the more homogeneous mixing and more rapid diffusion of species in the liquid state than in the solid state, the synthesis temperature of pure NbB2 phase was greatly decreased by the presence of molten NaCl/KCl salt. The NbB2 powders synthesized at 1000 degrees C had the largest specific surface area of 27.09m(2)/g and the lowest equivalent average particle size of 32nm, respectively.