Niobia, zirconia, ceria-niobia and ceria-zirconia oxide nanoparticles are prepared by soft chemical routes and show valuable textural properties, The pore volume and specific surface area keep significant values even after calcination at 873 K. According to DRX and STEM-EDX measurements, solid solutions are obtained in the case of ceria-zirconia, whereas separate phases are identified in ceria-niobia; in the latter case, however, W-Vis diffuse reflectance spectroscopy shows also the formation of defects (color centers) arising from a partial dissolution at the interface of the oxide phases. (C)2000 Elsevier Science B.V. All rights reserved.