Novel thermally stable and 2D mesoporous niobia phases were prepared by the evaporation induced self-assembly (EISA) with high surface areas (up to 211 m(2)/g). The pore size of these novel mesoporous niobium oxides was tuned in a wide range from 4.6 to 21 nm by increasing the aging temperature, aging time, and humidity of aging atmosphere. Mixtures of two nonionic surfactants, Pluronic P123 and Brij 35, were for the first time used to tune the pore structure of resultant mesoporous niobia phases which showed that the mesopore shape may be switched from cylindrical to ink-bottle. The niobia mesostructures obtained in this study were thermally stable up to 500 degrees C. These novel mesoporous niobium oxides with tunable pore sizes are highly promising as catalytic supports and a major component in the synthesis of porous Nb-containing mixed metal oxides, such as MoVTeNbOx catalysts for selective (amm)oxidation of propane.