The thermal behaviour and degradation mechanism of fully aromatic polyester, poly(oxy-1,4-phenyleneoxy-fumaroyl-bis-4-oxybenzoate), were studied by pyrolysis-gas chromatography and pyrolysis-gas chromatography/mass spectrometry at 500-700 degrees C, and by thermogravimetry. The influence of fullerene C-60 additives on thermal behaviour and thermal degradation was investigated. On the basis of pyrolysis products determined, the origin of the main degradation products (maleic anhydride, phenol, hydroquinone, phenyl ether, p-hydroxybenzoate-p'-phenol, etc.) was estimated. The fullerene is a well-known efficient acceptor of radicals and its presence influences the thermal degradation process of polymers shifting the decomposition from a radical pathway to a non-radical mechanism. Thermal degradation mechanism of poly (oxy-1,4-phenyleneoxy-fumaroyl-bis-4-oxybenzoate) is discussed in detail. (c) 2006 Elsevier Ltd. All rights reserved.