Organic and inorganic hybrid nanocomposites based on poly(ethylene 2,6-naphthalate) (PEN) and silicananoparticles were prepared by a melt blending process. In particular, polymer nanocomposites consisting mostlyof cheap conventional polyesters with very small quantities of inorganic nanoparticles are of great interest from anindustrial perspective. The crystallization behavior of PEN/silica hybrid nanocomposites depended significantly onsilica content and crystallization temperature. The activation energy of crystallization for PEN/silica hybrid nanocomposites was decreased by incorporating a small quantity of silica nanoparticles. Double melting behavior wasobserved in PEN/silica hybrid nanocomposites, and the equilibrium melting temperature decreased with increasingsilica content. The fold surface free energy of PEN/silica hybrid nanocomposites decreased with increasing silicacontent. The work of chain folding (q) for PEN was estimated as 7.28×10-20J per molecular chain fold, while theq values for the PEN/silica 0.9 hybrid nanocomposite was 3.71×10-20J, implying that the incorporation of silicananoparticles lowers the work required to fold the polymer chains.