The thermal degradation of hydrogenated nitrile-butadiene rubber (HNBR)/clay and HNBR/clay/carbon nanotubes (CNTs) nanocomposites was investigated with thermogravimetric analysis (TGA) by using Kissinger method, Flynn-Wall-Ozawa method and Friedman method. The activation energy sequence of HNBR and its nanocomposites is HNBR/clay/CNTs > HNBR/clay > HNBR. HNBR/clay/CNTs nanocomposites had higher char yield at 600 degrees C than HNBR/clay, which was attributed to the interaction of network between clay and CNTs. The activation energies of HNBR and HNBR nanocomposites had a sharply increase in the low conversion degree area and a slow increase in the high conversion degree area. The gases involved during thermal degradation in nitrogen atmosphere were studied by Fourier transform infrared spectroscopy coupled with TGA. The HNBR/clay/CNTs nanocomposites had lower thermal degradation rate than HNBR/clay. which could be attributed to that the clay-CNTs filler network reduced the diffusion speed of degradation products. The coexistence of clay and CNTs could form compact char layers with better barrier property than clay and thus improved the thermal stability of HNBR. (C) 2009 Elsevier BY. All rights reserved.