Thermal behaviour of Fe-based (Fe/Fe2O3 core)-polyoxocarbosilane (shell) nanocomposites, prepared by laser-induced co-decomposition of iron pentacarbonyl and hexamethyldisiloxane in the gas phase, was examined by using TGA technique. The thermal decomposition of the polymer shell of the nanocomposite is revealed as a two-stage (low- and high-temperature) evolution of methane. The importance of the low-temperature stage increases and that of the high-temperature stage decreases with increasing amount of the Fe/Fe2O3 cores. The results represent the first thermal data related to nanocomposite metal/polymer system and are explained in terms of heterogeneous catalysis of the polyoxocarbosilane decomposition by the Fe/Fe2O3 core. (C) 2005 Elsevier B.V. All rights reserved.