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THE study reported here has been undertaken to resolve the large discrepancies between reports of the temperature distribution in the combustion coal of a cigarette. Studies using bare thermocouples (refs 1–4 and R. G. Hook, paper presented at Twentieth Tobacco Chemists' Conference, Winston-Salem, North Carolina, November 1966) indicate that the highest temperatures occur on the central axis of the coal (the actual reported values vary considerably but are usually in the range 800–900° C during a puff, 700–800° C during the natural smoulder between puffs, and 800–850° C under steady state continuous draw conditions). Under all smoking regimes, the thermocouple-measured temperature decreases by up to 300° C along a radius from the maximum central temperature to the periphery of the coal, although one thermocouple study2 has reported the occurrence of occasional peripheral hot spots, with temperatures higher than the centre of the coal. (Ref. 2 contains a comprehensive compilation of more than forty studies of temperature measurements inside burning cigarettes prior to 1968.) In contrast, temperature measurements by X-ray observations of the melting of small metal particles placed within the cigarette5 indicate that the highest temperatures (900° C) occur at the periphery of the coal. Furthermore, measurements of the coal's surface temperature by radiation methods (ref. 5 and A. T. Lendvay, F. M. Watson III, and T. S. Laszlo, paper presented at the CORESTA/Tobacco Chemists' Joint Conference, Williamsburg, Virginia, October 1972) have recorded temperatures of about 850–920° C during a puff, 700° C (below the surface ash) during smoulder, and short-lived hot spots on the coal's surface as high as 1200° C (ref. 5).