Multi-walled carbon nanotube (MWCNT) and poly(ethylene 2,6-naphthalate) (PEN) nanocomposites are prepared by a melt blending process. There are significant dependence of non-isothermal crystallization behavior and kinetics of PEN/MWCNT nanocomposites on the MWCNT content and cooling rate. The incorporation of MWCNT accelerates the mechanism of nucleation and crystal growth of PEN, and this effect is more pronounced at lower MWCNT content. Combined Avrami and Ozawa analysis is found to be effective in describing the non-isothermal crystallization of the PEN/MWCNT nanocomposites. The MWCNT in the PEN/MWCNT nanocomposites exhibits much higher nucleation activity than any nano-scaled reinforcement. When a vary small quantity of MWCNT was added, the activation energy for crystallization is lower, then gradually increased, and becomes higher than that of pure PEN above 1.0 wt% MWCNT content. The incorporation of MWCNT improves the storage modulus and loss modulus of PEN/MWCNT nanocomposites. (c) 2005 Elsevier Ltd. All rights reserved.