Dehydration of D-xylose to yield furfural was carried out using bimetallic salts of a heteropolyacid as the catalyst at 160-220 degrees C in the DMSO/H2O mixtures. The effect of Sn/Cs molar ratio of the bimetallic salts of 12-tung-stophosphoric acid (PW) obtained by ultrasound-assisted coprecipitation on dehydration of D-xylose was investigated. The resultant catalysts were characterized by X-ray diffraction, N-2 adsorption, field emission scanning electron microscopy and energy dispersive X-ray (EDX). It was found that the Sn-Cs codoped PW catalysts retained the Keggin crystal structure of PW. Sn0.625Cs0.5PW was the most active catalyst in the dehydration of D-xylose into furfural. The maximum D-xylose conversion (close to 100 wt %) and furfural yield (63 wt %) were achieved at 200 degrees C for 3 h in DMSO/H2O mixtures. It was found that 16.7 wt % Sn0.625Cs0.5PW on a chitosan-derived support displayed similar catalytic activity to that of Sn0.625Cs0.5PW and good stability after recycling six times.