Solid acids catalysts based on niobium oxide incorporated on different supports (commercial fumed silica and gamma Al2O3, MCM-41 and SBA-15 silicas) have been synthesized, characterized by using XRD, N-2 sorption at -196 degrees C, XPS, Raman spectroscopy, NH3-TPD and pyridine adsorption coupled to FTIR spectroscopy, and tested for the dehydration of D-xylose to furfural. A monophasic water and biphasic water/toluene systems were compared, obtaining similar xylose dehydration activity but improving considerably the furfural selectivity when the toluene was employed as co-solvent. The gamma-Al2O3 support enhanced apparently the secondary reactions, as can be inferred for the lower furfural selectivity of the Al-12Nb catalyst compared with the silica supported catalysts. The highest conversion and furfural selectivity after 24h (84% and 93%, respectively) were found for the SBA-12Nb catalyst, at 160 degrees C in water/toluene. The niobia loading barely affected the xylose dehydration activity, but the catalyst with a 12 wt% showed higher furfural selectivity. Alternative N-2-stripping technique was also studied, improving the furfural yield and product purity in the stripped stream. (c) 2014 Elsevier B.V. All rights reserved.