The adsorption and reaction of SO2 with copper and copperoxide surfaces was studied by i n s i t u x‐ray photoelectron spectroscopy between 173 and 473 K and pressures ranging from UHV to 10− 1 mbar. It was found that a Cu2SO3 species acts as an intermediate in the formation of CuSO4 at T300 K in the formation of copper sulfide. The presence of gas‐phase oxygen was found to accelerate the surface reaction between SO2 and the substrates. In this communication we will focus on the experiments on Cu2O surfaces and discuss our results in the context of the SO2–flue‐gas cleanup process on copper oxide.