Thermal incineration of carbon monoxide (CO! has been evaluated using published kinetic data. Profiles of residence time versus fractional CO oxidation have been calculated and used in order to estimate incinerator size and auxiliary fuel requirements. The calculation procedure includes the effect of the reaction exotherm, under both adiabatic and non-adiabatic conditions. An apparent mean temperature of incineration may therefore be determined. This apparent mean will differ from the arithmetic mean of the stream temperatures to and from the incinerator and appreciable error may result if the arithmetic mean is used to calculate incineration time. The calculations have confirmed that CO is more difficult to oxidize than many volatile organic compounds (VOCs) and the rate of oxidation of intermediate CO should be included in evaluation of VOC incineration. Short residence times, of 0.5 seconds or less, favour minimization of both incinerator size and auxiliary fuel requirements for thermal incineration of both CO and VOCs. The optimum range of residence time for 99.5% CO incineration at an initial temperature of 1045 It appears to be approximately 0.3 to 0.4 seconds.