An improved synthesis of the phosphazene polymerization precursors, hexachlorocyclotriphosphazene, (NPCl2)(3) (1), and Cl3P=NSiMe3 (2) is reported. The addition of PCl5 to N(SiMe3)(3) in methylene chloride at 40 degrees C produced a mixture of phosphazenes which contained 76% of 1. However, the addition of N(SiMe3)(3) to PCl5 in methylene chloride at 0 degrees C, followed by the addition of hexane, provided 2 in 40% yield. The mechanism of the reaction is discussed.