SO2 adsorption and desorption on Pt/Pd mono- and bimetallic, gamma-Al2O3 supported catalysts were characterized. There are dependencies on both particle size and Pd:Pt ratio, and here particle size effects on the adsorption and desorption trends and surface species formed were evaluated using DRIFTS and TPD studies. Catalysts with a smaller particle size tended to form a greater amount of aluminum sulfate species, which decomposed at high-temperature. In contrast, catalysts with larger particle Sizes tended to form a greater amount of low-temperature decomposing and desorbing species, such as molecular SO2 and surface aluminum sulfite. In general, it was found that the amount of SO2 adsorbed and later desorbed during TPD decreased with increasing particle size. (C) 2017 Elsevier B.V. All rights reserved.