The removal of sulfur-containing compounds from petroleum products such as gasoline, diesel oil, and jet fuel is an important part of the petroleum refining industry. Most sulfur-containing compounds are removed by hydrodesulfurization (HDS), in which H2 gas is used to form hydrocarbons and H2S. [1] Some sulfur-containing compounds, notably dibenzothiophene and its alkylated derivatives, are refractory towards HDS and require (very) high reaction temperatures and pressures to be effective. Because environmental considerations and requirements mandate the removal of sulfur from fuels, so called “deep” HDS of refractory sulfur compounds is both difficult and expensive. Alternative “deep” desulfurization without H2, or high pressure or temperature, is desirable, and in recent years other techniques have been suggested to remove sulfurcontaining compounds from commercial fuels. Alternative methods that have been suggested include: (1) the relatively facile catalytic oxidation of sulfides by hydrogen peroxide or organic hydroperoxides, such as tert-butyl hydroperoxide, to yield sulfones. Numerous homogeneous and heterogeneous catalysts have been described in the literature. The sulfones formed then need be removed from the fuel product by either extraction, distillation, decomposition, or adsorption. Organic hydroperoxides are expensive and the use of hydrogen peroxide implies working with water, which then requires careful drying of the fuel ; (2) selective adsorption of refractory sulfides over solids, such as Cu-Y zeolite or S Zorb SRT (a zinc oxidebased reactive sorbent) ; (3) selective extraction, for example by using ionic liquids; (4) biodesulfurization; and (5) photo-oxidation. As part of our studies on electron transfer oxidations catalyzed by the H5PV V 2Mo10O40 polyoxometalate, we have recently found that H5PV V 2Mo10O40 catalyzes the electron transfer transfer–oxygen transfer oxidation of sulfides, RSR’ (R, R’=aryl, alkyl), to yield sulfoxides, RS(O)R’. The reactions take place by initial formation of a cation radical, RSR’+C, and a reduced polyoxometalate, H5PV VMo10O40. RSR’+C is then oxygenated by oxygen transfer from the polyoxometalate (Scheme 1). Interestingly, we observed that heteroaromatic sulfides, that is, thiophene derivatives, were not oxygenated, presumably due to their stability. We now report that such heteroaromatic thiophenes, such as benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (DMDBT), can be oxidatively polymerized by H5PV V 2Mo10O40 supported on an inert matrix such as silica. The polymer formed is adsorbed or deposited onto the solid and in this way these heterogeneous catalysts can be used to remove refractory aromatic sulfides from hydrocarbons down to nondetectable levels. The catalyst can be regenerated by pyrolysis at 300–350 8C. In preliminary experiments benzothiophene (84 mm) was reacted with H5PV2Mo10O40 (30 mm) dissolved in acetic acid (1 mL) at 70 8C for 1 h. Different from a reaction using thioanisole as substrate, no sulfoxide was formed but benzothiophene was almost completely consumed and a brown–black insoluble material was formed. Similarly, mixing benzothiophene with H5PV2Mo10O40 at 22 8C yielded a green solution, the UV/Vis spectrum of which indicated the formation of a reduced polyoxometalate: H5PV VMo10O40. Thus, a reaction pathway can be assumed in which H5PV2Mo10O40 can activate benzothiophene by electron transfer to yield a benzothiophene cation radical (Scheme 2). The benzothiophene cation radical