The kinetics of the thermal decomposition of penta bromo chlorocy-clohexane (PBCCH), a flame retardant employed in foamed polystyrene, were determined by monitoring the rate of HBr/Br2, evolution at temperatures between 195-240°C. The early stage of the decomposition is catalyzed by iron. The activation energy for the initial decomposition is approximately 32 Kcal/mole. The principle organic decomposition products are dibromo-, bromochloro- and tri-halobenzenes.