Oxidation of coals of different rank and containing different amounts of sulfur was carried out using O-2/Na2CO3. The surface chemical state of some elements (C, 0, S) and their content was studied by X-ray photoelectron spectroscopy and compared to those of coal samples oxidized with peroxyacetic acid solution. The extent of surface oxidation depended on the rank of coal, bulk oxygen content of the starting sample, and the type of oxidizing agent. The oxidizing process led to the increase of the amount of oxidized forms of sulfur-sulfoxides and sulfones. The changes in the amount of oxygen-containing species were also discussed.