Abstract: Burning of p-xylene and solvent during oxidation is the critical side reaction.In this paper the burning mechanism is analyzed and the kinetics model is developed on the basis of the radical chains reaction mechanism.Model parameters were determined by data fitting of the CO_x transient response curves.The experimental results showed that, the CO_x generating rates increased remarkably with increasing Co/Mn ratio and catalyst concentration.As compared with the main reaction, the burning rate was more sensitive to the change of the ratio of cobalt vs manganese, but less to bromine concentration.