Abstract A method for enhancing the molecular weight of poly( p -dioxanone) (PPDO) has been provided in this investigation. Higher molecular weight biodegradable polymers have been prepared by chain-extending method from lower molecular weight PPDO using toluene-2,4-diisocyanate (TDI) as a chain extender. The prepolymers and the resulting polymers were characterized by 1 H NMR, DSC, WAXD, and TG. The results show that TDI is an effective chain extender for PPDO. Comparing the chain-extended polymers with PPDO prepolymers, no obvious change in melting temperatures and crystal structures has been observed except that glass transition temperatures increase. The studies of the thermal-oxidative degradation of PPDO show that the thermal stability of chain-extended PPDO is higher than that of PPDO prepolymers.