PURPOSE: To provide a method for treating an exhaust gas so designed that, in producing an aromatic carboxylic acid by oxidation of an aromatic compound with molecular oxygen in an oxidation reaction vessel, even in case organobromine compound (s) such as methyl bromide is contained in the exhaust gas discharged from the reaction vessel, such various organic compounds including the methyl bromide can be oxidized and removed economically and in high efficiency while suppressing the decline in catalytic activity.

CONSTITUTION: This method is designed to treat the exhaust gas generated during the production of an aromatic carboxylic acid by oxidation of an aromatic compound with molecular oxygen in an oxidation reaction vessel. Specifically, the exhaust gas is preliminarily oxidized by bringing it into contact with a 1st oxidative catalyst composed of a group VIIA metal or its compound and a group IB metal or its compound, and then brought into contact with a 2nd oxidative catalyst composed of a group VIA metal or its compound and a noble metal to effect oxidation.