The reaction process of catalytic combustion of ARB on CuFe2O4 in the presence and absence of O2 was studied by in situ DRIFT spectroscopy. The results showed that the decomposition of the sulfonic group of ARB molecule was not affected by the reaction atmosphere, but the decompositions of azo group and aromatic ring were markedly affected by the presence or absence of O2. The catalytic combustion of ARB was faster in air atmosphere than that in N2 atmosphere, and ARB could be completely oxidized to CO2 and nitrate at 300 degrees C. But in N2 atmosphere, it was very difficult for the decomposition of ARB to complete at 300 degrees C, even though air was introduced following this process. The temperature required for the rapid and complete decomposition would be as high as 500 degrees C.