In this study, we have synthesized zirconia-silica nanocomposites with different ZrO2 content (50% and 30%) using a modified 501-gel method, based on TEOS-Zr(W)-NO3- -polyalcohols-H2O sols that successfully gelified to homogenous gels. The gels obtained at room temperature have been dried and then thermally treated at up to 150 degrees C when a redox reaction took place between the organic polyalcohol and zirconia nitrate, evidenced by DTA analysis, leading to the formation of zirconia nanoparticles precursors in the pores of silica matrix. The obtained precursors have been characterized by thermal analysis and FTHL spectroscopy, and further annealed at higher temperature in the range 500-1200 C. XRD analysis of the resulted composites have evidenced the presence of nanocrystalline tetragonal zirconia as single crystalline phase up to 1200 degrees C in the case of 30% ZrO2 samples, and up to 1000 degrees C for the 50% ZrO2 samples. In the later samples, after being annealed at 1200 degrees C, several crystalline phases have been present. For all nanocomposites we have obtained a homogenous dispersion of zirconia within the silica matrix, evidenced by Zr and Si elemental maps, performed by SELVI-[DX analysis. (C) 2014 Elsevier B.V. All rights reserved