Abstract: The adsorption behavior of SO2 and NO on Na-γ- Al2O3, a sorbent used for simultaneous removal of SOx (98.0%~99.0% SO2) and NOx (90%~99% NO) form flue gas, was investigated in an atmospheric fixed bed reactor at 150 ℃ by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The volumetric composition of feed gas was 0.51% SO2, 0.1% NO, 4.5% O2, Ar as balance. For the adsorption behavior of a single pollutant, SO2 is adsorbed easily and no SO2 is oxidized to form SO42- (at least SO42- can not be detected on the surface of sorbent), whereas NO is adsorbed more difficultly compared with SO2. The adsorption capacity of NO is low, and a small amount of NO2 or surface nitrate is formed. The adsorption capacities of SO2 and NO are improved in the presence of O2. NO and SO2 can be adsorbed simultaneously in the presence or absence of O2. There are interactions between SO2 and NO on Na-γ- Al2O3. The presence of NO favors adsorption of SO2 and formation of SO42-. Whereas effect of SO2 on adsorption of NO is complicated. SO2 can promote NO oxidation to form NO2 or surface nitrate; on the other hand, SO2 can result in desorption of NO2. The adsorption capacities as well as interactions of NO and SO2 are enhanced by O2.