A method for the synthesis of well-defined mono-, di-, and mixed-telechelic polyphosphazenes produced via a living cationic polymerization of phosphoranimines is described. Amino phosphoranimines R-NH(CF3CH2O)(2)P=NSiMe3 (R=Ph-, p-BrPh-, p-H3CPh-, CH2=CHCH2-, and CH2=CHPh-) were synthesized via a reaction between a bromophosphoranimine and the appropriate organic amine. Ditelechelic polymers [R-NH](2)-[Cl2P=N](n) were prepared by quenching living poly(dichlorophosphazene) chains, [Cl3P=N(Cl2P=N)(n)-PCl3](+)[PCl6](-) with small quantities of the amino phosphoranimines. Cationic initiators of the amino phosphoranimines were also generated using PCl5 and were used to polymerize Cl3P=NSiMe3, to give monotelechelic poly(dichlorophosphazenes). In addition, a mixed telechelic system was produced by the termination of an allylamino monotelechelic poly(dichlorophosphazene) chain with a bromoanilino phosphoranimine. In all cases, displacement of the chlorine atoms with sodium trifluoroethoxide yielded hydrolytically stable telechelic polymers with controlled molecular weights and low polydispersities.