Two poly(ethylene succinate) (PES) based nanocomposites containing low loadings (0.5 and 1.0 wt%) of octaisobutyl-polyhedral oligomeric silsesquioxanes (oib-POSS) were prepared via a solution and casting method. The scanning electron microscopy observation demonstrated the fine dispersion of oib-POSS in the PES matrix. The nonisothermal cold and melt crystallization behaviors, isothermal melt crystallization kinetics, crystalline morphology, crystal structure, and mechanical properties of PES and its nanocomposites were studied. Oib-POSS not only enhanced the nonisothermal cold and melt behaviors but also accelerated the overall isothermal melt crystallization process of PES in the nanocomposites, indicating its nucleating agent effect. Oib-POSS did not modify the crystal structure of PES in the nanocomposites; furthermore, oib-POSS and PES crystallized separately in the nanocomposites. Oib-POSS obviously enhanced the Young's modulus and yield strength while still maintained relatively good ductility of PES in the nanocomposites, suggesting the efficient reinforcing effect of oib-POSS on the mechanical properties of PES. (C) 2017 Elsevier B.V. All rights reserved.