Catalytic oxidation in a reverse flow reactor is an attractive process for the decontamination of air polluted with volatile organic compounds (VOCs). In this paper several aspects of operating this type of reactor for air purification under strongly varying conditions will be discussed.For a successfit operation of such reactor a minimum amount of combustibles is required, and a simple theory is developed to predict this minimum value. This minimum amount is strongly influenced by the reaction kinetics, the heat transport in the packed bed and the adiabaticity of the reactor. To cope with a too low temperature level in the reactor for a complete conversion, an electrical heating device should be installed in the centre of the reactor bed to increase locally the temperature rapidly and efficiently. To control the maximum temperature in case of too high concentrations, extra air should be added to the feed. L'oxydation catalytique dans un reacteur a ecoulement inverse est un procede inteessant pour la decontamination de I'air pollue par des composes organiques volatils (VOC). Dans cet article, plusieurs aspects du fonctionnement de ce type de reacteur pour la purification de I'air dans des conditions extr6mement variables seront analyses.Pour le bon fonctionnement d'un tel reacteur, un apport minimum en combustible est necessaire, et une theorie simple a ete etablie afin de predire cette valeur minimum. Cet apport minimum est fortement influence par la cinetique de la reaction, le transfert de chaleur dans le lit gami et I'adiabicite du reacteur. Pour eviter d'avoir une temperature trop basse dans le reacteur en vue d'une conversion complete, un dispositif de chauffage electrique doit 6tre installe au centre du lit du reacteur afin d'augmenter localement la temperature de faqon rapide et efficace. Pour contrder la temperature maximum en cas de concentrations trop fortes, de l'air doit 6tre ajoute a I'alimentation.Keywords: catalytic combustion, reverse flow operation, air purification. xhaust air from laboratories or factory buildings can be E contaminated with volatile organic compounds (VOCs).In order to reduce the emission of VOCs, a large number of methods are available. The economically most attractive method depends on the specific conditions in each case, including the concentration and nature of the contaminants and the flow rate. Moreover, the polluted air stream might show strong variations in flow rate as well as in concentration and chemical character of the pollutants. In the case of valuable contaminants, separation methods with recovery of the organic compounds might be considered. Examples in this area are membrane separation and pressure swing adsorption. These methods have in common that the contaminants are concentrated in the first step of the process. The second step is the recovery of the contaminants. Another group of purification methods is composed of destructive processes like thermal and catalytic combustion, which are non-selective. Many modifications or combinations are possible, as fo...