By modified sol-gel method, ZnO/SiO2 and Zn2SiO4/SiO2 nanocomposites were obtained. ZnO dispersed in silica matrix results from zinc carboxylate thermal decomposition. Zinc carboxylate was synthesized in situ in hybrid silica gels via redox reaction. Evolution of ZnO in SiO2 matrix depends on temperature and system composition.