Zinc-oxide nanoparticles embedded in silica glass were fabricated by ion implantation of Zn+ ions of 130 keV and up to a dose of 2×1017 ions/cm2, followed by thermal annealing in O2 atmosphere at 800°C and for 1h. Glancing-incidence x-ray diffraction and transmission electron microscopy results show zinc crystalline nanoclusters with an average diameter of 13nm and placed around a R p=70nm, in the as-implanted sample. The thermal oxidation promotes the diffusion of the Zn atoms preferentially towards the surface of the silica where ZnO particles of 65nm in diameter where found and a small diffusion toward the bulk where ZnO clusters of 5nm in diameter were observed. A relatively strong exciton emission peak from the ZnO particles was observed in the photo-luminescence spectrum at 380nm. © 2006 Materials Research Society.