The effects of high temperature annealing in an oxidizing atmosphere on defect evolution have been studied using global and local techniques. Modeling the evolution of silicon oxide precipitates requires knowledge of the precipitate stoichiometry. In this study we followed precipitate size evolution during the annealing process. The stoichiometry was determined using two different methods: first, results were obtained using Laser Scattering Tomography (LST) technique to determine the size and density of precipitates and compared with model predictions, considering both SiO and SiO2 cases. Then, the precipitate composition and stoichiometry were measured directly, using Electron Dispersive X-ray Spectroscopy (EDX) in an Transmission Electron Microscope (TEM). It is shown that the most probable stoichiometry is SiO and both methods provide similar results. (C) 2012 Elsevier B.V. All rights reserved.