New reactive polymers with pendant halomethyl groups were successfully synthesized by polyaddition reactions of bis(epoxide)s with bis(chloroacetoxy) ester such as 1,4-bis[(chloroacetoxy) methyl] benzene (BCAMB) or 1,4-bis[(bromoacetoxy)-methyl]benzene (BBAMB) using quaternary onium salts or crown ether complexes as catalysts, The polyaddition reaction of diglycidyl ether of bisphenol A (DGEBA) with BCAMB proceeded very smoothly with high yields (83-96%) by the addition of quaternary onium salts such as tetrabutylphosphonium bromide (TBPB) or crown ether complexes such as 18-crown-6/KBr as catalysts to produce high molecular weight polymers, although the reaction occurred without any catalyst to give low molecular weight polymer in low yield at 90 degrees C for 48 h. It was also found that the reaction proceeded smoothly in aprotic polar solvents such as N-methyl-2-pyrrolidone (NMP) and N,N-dimethylacetamide (DMAc) to produce high molecular weight polymers, Polyaddition reactions of DGEBA or digylcidyl ether of ethylene glycol (DGEEG) with BBAMB, other bis(chloroacetoxy) esters or bis(bromoacetoxy) esters using TBPB in DMAc also proceeded smoothly to give the corresponding polymers. The resulting poly(ether-ester)s contain reactive halomethyl groups as side chains, which were introduced during main chain formation.