Aromatic polyester nanocomposites based on poly(ethylene 2,6-naphthalate) (PEN) and carbon nanotube (CNT) were prepared by melt blending using a twin-screw extruder. Modification of CNT to introduce carboxylic acid groups on the surface was performed to enhance intermolecular interactions between CNT and the PEN matrix through hydrogen bonding formation. Morphological observations revealed that the modified CNT was uniformly dispersed in the PEN matrix and increased interfacial adhesion between the nanotubes and the PEN, as compared to the untreated CNT. Furthermore, a very small quantity of the modified CNT substantially improved thermal stability and tensile strength/modulus of the PEN nanocomposites. This study demonstrates that the thermal, mechanical, and theological properties of the PEN nanocomposites are strongly dependent on the uniform dispersion of CNT and the interactions between CNT and PEN, which can be enhanced by slight chemical modification of CNT, providing a design guide of CNT-reinforced PEN nanocomposites with a great potential for industrial uses. (C) 2008 Elsevier Ltd. All rights reserved.