Nanostructured niobium oxides were synthesized by hydrothermal treatment using an amorphous Nb2O5 as precursor. The modification by hydrothermal treatment in the presence of oxalic acid or hydrogen peroxide resulted in versatile catalysts with many different properties verified by several characterization techniques. XRD analysis demonstrated the crystallinity increase. Significant morphological changes were observed by TEM, being possible to observe the presence of nanorods for the material treated with oxalic acid and nanospheres for the material treated in the presence of H2O2. Modifications in the porous structure were also observed, as well as the increase in BET specific area. This significant difference compared to precursor resulted in catalysts with higher performance than Nb2O5 in decomposition of methylene blue dye (MB) by heterogeneous fenton-like reactions and photocatalysis under UV light irradiation. (C) 2016 Elsevier B.V. All rights reserved.