• The ability of perfluorinated solvents to solubilize gases, together with their unique phase properties, have been exploited in a system for oxidation of aldehydes to acids, sulfides to sulfoxides and sulfones, and alkenes to epoxides. The reactions are carried out in the presence of dissolved O2, using a transition metal (Ru, Ni) catalyst with perfluorinated ligands, in a perfluoro(decahydronaphthalene)/toluene solvent mixture under monophasic conditions at 64oC. On cooling, phase separation takes place, enabling the product to be isolated from the toluene phase, and the catalyst system to be recycled in the fluorous phase: Angew. Chem. Int. Ed., 36, 1454 (1997).