A calculation procedure has been developed for evaluation of residence time for thermal incineration of volatile organic compounds (VOCs) to CO 2 and H 2 O which takes into account change in reaction rate with temperature, heat losses through the walls of the incinerator and change in concentration of both oxygen and the VOC. The values for residence time obtained by means of this procedure are typically less than 50% of those obtained by using an arithmetic mean incineration temperature. Use of an arithmetic mean incineration temperature to evaluate residence time is inappropriate because it does not satisfactorily account for the rapid increase in the rate of VOC incineration with temperature, which follows an Arrhenius relationship.An approximate version of the above procedure has been developed for preliminary calculations and gives good agreement with the results obtained by means of the more rigorous model, for both adiabatic and non- diabatic conditions. Experimental studies to test the model's predictions are strongly recommended.