Most polyphosphazenes are made from the chloro polymer [PCl2N]n. However, the high expense, inefficiency and irreproducibility in the syntheses [PCl2N]n hinder the use of polyphosphazenes in industry. The aim of the work is to study the basic chemistry of chlorophosphazenes in order to solve some of these problems. In the presence of water, the reactions of the weak base [PCl2N]3 with the Lewis acids AlBr3, AlCl3, and SbCl5 give the superacid complexes [PCl2N]3.HMXm+1 (HMXm+1 = HAlCl4, HAlBr4, HSbCl6), as by-products in the former two cases and as the only isolated compound for the latter. These compounds have been prepared in high yield by the reactions of [PCl2N]3, MXm and HX. Variable temperature NMR studies show that all [PCl2N]3.HMXm+1 are highly fluxional in solution, even at low temperatures. The possible involvement of superacids in various aspects of chlorophosphazene chemistry will be discussed.