Interactions between CO2 and SiO2 films thermally grown on Si have been studied using O-18 and C-13 as isotopic tracers associated with ion beam analysis (IBA) depth profiling techniques. From secondary ion mass spectrometry (SIMS) measurements no carbon from CO2 is detected in the silica while it is found in Si. These results suggest that CO2 diffuses through the silica. Exchanges of oxygen between CO2 and silica can be observed from O-18 to O-16 SIMS signals variation. The oxygen concentration depth profiles were determined quantitatively using the narrow resonance near 151 keV in the O-18(p,alpha)N-15 nuclear reaction (Narrow Resonance Profiling, NRP). We demonstrate that two distinct oxygen exchanges processes coexist and we determine the diffusion coefficient of the CO2 molecule in the silica at 1100 degrees C. (C) 2013 Elsevier B.V. All rights reserved.