A series of biodegradable isosorbide-based copolyesters poly(butylene succinate-co-isosorbide succinate-co-polyethyleneoxide succinate) (PB(x)I(y)E(z)S) were synthesized via bulk polycondensation in the presence of dimethyl succinate (DMS), 1,4-butanediol (BDO), poly-(ethylene glycol) (PEG) and isosorbide (ISO). The crystallization behaviors, crystal structure and spherulite morphology of the copolyesters were analyzed by differential scanning calorimetry (DSC), wide angle X-ray diffraction (WAXD) and polarizing optical microscopy (POM), respectively. The results indicate that the crystallization behavior of the copolyesters was influenced by the content of isosorbide succinate (IS) and polyethyleneoxide succinate (PEOS) units, which further tuned the mechanical and biodegradable properties of the copolyesters. The PB(x)I(y)E(z)S copolyesters, compared to pure poly(butylene succinate), showed lower crystallization temperature, melting temperature, degree of crystallinity and degradation rate while a significant increase in glass transition temperature with increasing isosorbide content. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121:2291-2300, 2011