Linear phosphazene dichloride oligomers Cl(NPCI2)3n, PCI4(LPNC) were prepared by the reactipn of phosphazene dichloride trimer (NPC12)s with phosphorus pentachloride PCIs.It was found by the chemical analysis that the hydrolysis of the terminal chlorine atoms in LPNC occurred more rapidly than the middle chlorine atoms contained in the linear molecule of LPNC.The products obtained by the hydrolysis of the middle chlorine atoms of LPNC was HO[NHP(O)OH]sneP(O)(OH)2 (a).Those products(a)were again hydrolyzed and became ammonium orthophosphate. The hydrolysis of LPNC was of first-order and the ca1culated activation energy was about 14kcal/mol.The dissociation constant K and the free energy of dissociation dG of (a) were calculated to be K=7.0-7.4x10-8 and dG=2.9 kca1/mol, respectively.Upon heating (a) the polycondensation reaction occurred evolving water and ammonia.