The effect of modification of ?-FeOOH with niobium, applied to dehydration reaction of xylose, was evaluated by experimentally and theoretically methods. The experimental data confirmed that the materials were obtained by characteristic peaks in the X-ray diffractometer analysis. Inductively coupled plasma mass spectrometry analysis defined the percentage of Nb as 0 for pure ?-FeOOH and 9.5 % w/w (?-FeOOH/Nb) for doped. In relation to obtaining furfural, the doped material presents a conversion improvement of 290 % when compared to pure catalyst. Theoretical calculations were useful in understanding the preferential route of the mechanisms proposed by the obtained potential energy values. To understand the preferred routes, the most favorable position of xylose in relation to ?-FeOOH was initially calculated. From this, the favoring of furfural formation was calculated based on the routes of the proposed mechanisms and the energy values indicated that the furfural formation is more likely by the doped material.