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We present molecular dynamics simulations directed at understanding self-limiting oxidation of nanoclusters. Atomic oxygen is inserted in an atom-by-atom way in the silicon bonds to form silicon oxide. First, we focus on planar oxidation to calibrate our model and test its capabilities. Then, we present results on oxidation of 50 Å diam silicon spheres. Kinetic causes of self-limitation are investigated by drawing a map of the local stress in the Si/SiO 2 system. We obtain stresses in contrast to in continuum models. For thin oxides, we find in particular tensile pressure in the silicon core and a pressure gradient in the oxide shell. We investigate the effect of pressure gradient on the O 2 transport within the framework of Nerst-Eintein's transport equation. We find that a pressure gradient compatible with experimental estimates yields self-limitation of the oxidation kinetics.