The thermal degradation of a bisphenol-A based epoxy resin (EP 274) cured with 4,4’ -diaminodiphenyl methane (DDM) and with phthalic anhydride (PA) was studied using pyrolysis gas chromatography. Conclusive evidence for some of the degradation mechanisms of these resins was obtained by pyrolysing samples containing various 14C labelled groups and analysing the products using a combined gas chromatography and radiochemical technique.