Carbon nanotubes ( CNTs)/polymer composites were characterized through Raman spectroscopy when heated. Functionalized-CNT composites showed a noticeable shift of Raman G band while pristine CNT composites showed a slight shift. Raman G band shift of as-produced epoxide-grafted CNT composites was more significant than that of amino-grafted CNT composites. Further mechanical tests validated properties of epoxide-grafted CNT composites were superior to those of amino-grafted CNT composites even though both nanocomposites revealed significant improvements in comparison with pristine CNT composites. The possible reasons may come from different functionalization density and functionalization-dependent interfacial structures. These experimental results indicate that Raman G band shift is an indication of load-transfer of nanocomposites and it can be used to quantify the effect of CNT functionalization on the composite load-transfer. (c) 2008 Elsevier B. V. All rights reserved.