The polyphosphazenes {[NP(O2C12H8)](0.75)[NP(O-C6H4-CH2-CH2-CH2-OH)(O-C6H5)](0.25)}(n) and ([NP (O2C12H8)](0.75)[NP(O-C6H4-(CH2-CH2-CH2-OH))(2)](0.25)}(n), having pendant OH groups, have been synthesized by the direct reaction of the intermediate {[NP(O2C12H8)](0.75)[NP(Cl)(2)](0.25)}(n) with the heterobifunctional reagent HO-C6H4-(CH2)(3)OH in the presence of Cs2CO3 which specifically activates the phenolic OH in the presence of the alkylic hydroxyl. The Sn(Oct)(2) promoted ring-opening polymerization of epsilon-caprolactone at 110 degrees C on the terminal OH groups gave well defined polycaprolactone (P-CL) branched polyphosphazenes in good yield. The effects of the branching on the crystallization behaviour as well as the thermal stability of the new polymers have been studied. (C) 2011 Elsevier Ltd. All rights reserved.