Nanocrystalline tantalum and tungsten nitrides were synthesized by a two-step ammonolysis reaction of transition metal chlorides. The first step involves ammonolysis of tantalum and tungsten chlorides at room temperature using anhydrous chloroform as the solvent. A second step consists of heat treatment of these as-prepared powders under anhydrous NH3 atmosphere leading to the formation of tantalum and tungsten nitride nanocrystallites at relatively low temperature (600 degrees-675 degrees C). The ammonolysis, nitridation, structure, morphology, surface area, density, and electronic conductivity of the nitrides obtained were studied and characterized. The electrochemical responses of these nitrides were also measured by cyclic voltammetry using 1M KOH electrolyte.