AbstractMultiwalled carbon nanotube (MWCNT)/epoxy composites are prepared, and the characteristics and morphological properties are studied. Scanning electron microscopy microphotographs show that MWCNTs are dispersed on the nanoscale in the epoxy resin. The glass‐transition temperature (Tg) of MWCNT/epoxy composites is dramatically increased with the addition of 0.5 wt % MWCNT. The Tg increases from 167°C for neat epoxy to 189°C for 0.5 wt % CNT/epoxy. The surface resistivity and bulk resistivity are decreased when MWCNT is added to the epoxy resins. The surface resistivity of CNT/epoxy composites decreases from 4.92 × 1012 Ω for neat epoxy to 3.03 × 109 Ω for 1 wt % MWCNT/epoxy. The bulk resistivity decreases from 8.21 × 1016 Ω cm for neat epoxy to 6.72 × 108 Ω cm for 1 wt % MWCNT/epoxy. The dielectric constant increases from 3.5 for neat epoxy to 5.5 for 1 wt % MWCNT/epoxy. However, the coefficient of thermal expansion is not affected when the MWCNT content is less than 0.5 wt %. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1272–1278, 2007