AbstractPolychlorophosphazenes2can easily be obtained by thermal condensation of dichlorophosphinoyliminotrichlorophosphorane (1) under atmospheric pressure at 240–290°C, pure POCl3being eliminated. The different stages of the reaction were studied by chemical analysis,31P NMR, IR spectroscopy, and thin layer chromatography. The procedure enables one to obtain polymers of low and high molecular weights. The samples do not contain any cyclic or reticular polymers. Species of low molecular weights can be separated from those with high molecular weights by treatment with heptane. The total yield of phosphorus is 100% with regard to the starting material. Substitution products (Cl by OCH2CF3) are obtained which are identical with those obtained with the polychlorophosphazenes prepared via classical metho