The use of liquid hydrazine(N2H4)as a nitrogen source for nitridation reactions has been restricted because of safety, purity, and difficulties in using a liquid source. Hydrazine cyanurate (HC) is a stable solid complex ofN2H4which can be easily handled and purified before use and which evolves pureN2H4upon heating, thus making it a promising source ofN2H4for nitridation reactions. In this article, a process for the synthesis of HC has been developed which decreases theH2Ocontent of the evolvedN2H4from 10% whenH2Owas used as the solvent in the synthesis of HC to 0.7% by replacingH2Owith dimethylsulfoxide as the solvent in the synthesis of HC. The use of the purified HC is demonstrated as a solid source in the nitridation of (100) GaAs substrates at 200 °C in a low pressure chemical vapor deposition reactor. The nitridated GaAs surfaces were analyzed by x-ray photoelectron spectroscopy and were found to be primarily comprised of GaN, GaAs, andGa2O3.The ratio of the constituent peak heights in the Ga3dpeak of GaN toGa2O3was 2.25 in the grown nitride films. The oxide impurities were most likely due to incomplete removal of the native substrate oxide formed prior to growth and were not a product of the nitridation.