The crystallization, melting behavior, and spherulitic growth kinetics of biodegradable poly(ethylene succinate-co-6 mol % butylene succinate) [P(ES-co-6 mol % BS)] were investigated and compared with those of the homopolymer poly(ethylene succinate) (PES) in this work. The crystal structure of P(ES-co-6 mol % BS) was the same as that of neat PES, but the crystallinity decreased slightly because of the incorporation of the butylene succinate content. The glass-transition temperature decreased slightly for P(ES-co-6 mol % BS) compared to that for neat PES. The melting point of P(ES-co-6 mol % BS) decreased apparently; moreover, the equilibrium melting point was also reduced. Two melting endotherms were found for P(ES-co-6 mol % BS) after isothermal crystallization; this was ascribed to the melting, recrystallization, and remelting mechanism. The spherulitic growth rate of P(ES-co-6 mol % BS) was slower than that of neat PES at a given crystallization temperature. Both neat PES and P(ES-co-6 mol % BS) exhibited a crystallization regime II to III transition; moreover, the crystallization regime transition temperature of P(ES-co-6 mol % BS) shifted to a low temperature compared with that of neat PES. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 105-111, 2011