As-received multiwalled carbon nanotubes (MWCNTs) were first treated by a 3 : 1 (v/v) mixture of concentrated H2SO4/HNO3 and further functionalized by ethylenediamine/dicyclohexylcarbodiimide/tetrahydrofuran solution. MWCNT/epoxy nanocomposites were prepared. Their cure behaviors were investigated by dynamic differential scanning calorimetry. Quantitative analysis of the activation energy as a function of the degree of curing was carried out by the Flynn-Wall-Ozawa method. The fitted multiple regression equations for values of the activation energy of different systems were obtained. MWCNTs have the retardation effect on the cure reaction of epoxy resin, while the functional groups on the surface of amine-modified MWCNTs could accelerate the cure reactions. Thermal stability was studied by thermogravimetric analysis. The filling of amine-modified MWCNTs is beneficial to lower the cure activation energy and improve thermal stability of the nanocomposite. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 2980-2988, 2008