The high temperature kinetics of silane-nitrous oxide mixtures, highly diluted in argon, have been examined behind reflected shock wave using Atomic Resonance Absorption Spectroscopy of O atoms. The temperatures and pressures range from 1725 to 2584 K and from 231 to 601 kPa, respectively. At low temperature, the oxygen atom concentrations reached a steady state level after few hundreds of μs. At high temperature, the initial fast increase of oxygen atom concentration was followed by a period of consumption. A kinetic model able to reproduce the present and previous experimental results has been developed.