The pristine sodium montmorillonite (MMT) was organically modified with hexadecyltrimethylammonium bromide (HTAB) at different contents. The organoclay was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy, energy dispersive X-ray techniques, and thermogravimetric analysis. Then, poly(butylene succinate) (PBS) nanocomposites were prepared by melt-mixing process using maleic anhydride-grafted PBS (PBS-g-MA) as compatibilizer. It was found that the mechanical properties of PBS nanocomposites filled with organoclay were apparently higher than that of the nanocomposite filled with MMT. This is attributed to the better filler–matrix interactions between PBS and the organoclay and the better filler dispersion. This is verifiable through the XRD, scanning electron microscopy, and transmission electron microscopy. The addition of PBS-g-MA further improved the mechanical properties. It was also found that our laboratory synthesized organoclay modified with HTAB has provided a better reinforcing efficiency when compared with the commercial octadecylamine-modified organoclay. Besides that the thermal properties of PBS nanocomposites were studied through differential scanning calorimetry. POLYM. ENG. SCI., 2013. © 2013 Society of Plastics Engineers