A rigorous thesmochemical analysis of the pyrolysis of aromatic chlorides shows that destruction efficiencies in excess of 99.999 percent are possible in a reducing atmosphere at temperatures near 1000 K. This process used for the destruction of chlorinated organic ompounds yields non-halogenated hydrocarbons and hydrochloric acid as reaction products. Qualitative batch experiments on chloromethane and polychlorinated biphenyls (PCBs) showed that such efficiencies could be obtained in residence times below 7 minutes at 1273 K. Qualitative continuous flow experiments demonstrated that these efficiencies are actually obtained in residence times less than 1.8 seconds for chloromethane and 4.4 seconds for the PCB mixture Arochlor 1254. A simple kinetic analysis shows that the Aroclor 1254 radicals are produced by the decomposition of hydrocarbon solvents [n-hexane and iso-octane) used to provide the reducing atmosphere. The difference in residence times between batch and continuous flow reactors is explained by temperature gradient effects in batch reactors and the associated heat flux limiting rate phenomenon due to endothermic reaction steps.