In-situ diagnostic measurements and reactor modeling have been used to study N2O dissociation by r.f. discharges. Measurements have been conducted at 1 Torr (i.e. 133.3 Pa) and at a r.f. power density from 4.8 to 22.7 mW/cm2. We developed a complete reactor modeling involving an electrical discharge model coupled to a mass transfer model. Only an electrical discharge model accounting for the negative ion conversion from O- to NO- allowed a good coherence between measured and predicted power densities. The electron-N2O dissociation rates, obtained from the electrical model, are then used in the mass transfer model, including eight species [N2O, N2, O2, NO, NO2, N, O(3P) and O(1D)]. The corresponding results are in good agreement with the experimental results concerning the N2 and O2 productions and the N2O consumption. These results have particularly shown that N2 and O2 are the most abundant products (>1014 molecules/cm3).