The combustion behavior and thermal-oxidative degradation of polypropylene/clay nanocomposite has been studied in this paper. The influence of compatibilizer, alkylammonium, organoclay, protonic clay and pristine clay is considered, respectively. The decrease of heat release rate (HRR) is mainly due to the delay of thermal-oxidative decomposition of the composites. The active sites on clay layers can catalyze the initial decomposition and the ignition of the composites. On the other hand, the active sites can catalyze the formation of a protective coating char on the samples. Moreover, the active sites can catalyze the dehydrogenation and crosslinking of polymer chains. Accordingly, the thermal-oxidative stability is increased and HRR is decreased. (c) 2005 Elsevier Ltd. All rights reserved.