Abstract: Changes of the sulfate product and optical coefficients during the heterogeneous reaction of SO2 on the surface of hematite at different temperatures were investigated using in situ diffuse reflectance Fourier transform infrared spectroscopy (DFTIRS), ion chromatogram (IC), and transmission electron microscopy (TEM). Simulations revealed that within the ambient temperature of 15-45 ℃, the yield and velocity of sulfate product, absorption coefficient, and backward scattering coefficient firstly increased at 15-35 ℃ and then decreased at 35-45 ℃. At persistent temperature, the velocity of sulfate production showed an initial increase followed by a decrease and finally stabilized. There was a high exponential correlation between the optical coefficients and the amount of sulfate product generated. This result is important in understanding the heterogeneous reaction of SO2 on the surface of hematite in the environment and the assessment of this reaction’s impact on sulfate production and radiative forcing, considering the phenomenon of global warming.