Sintering of fine silicon powder was studied using thermogravimetric experiments associated with dilatometry. The reduction of the silica layer at the particle surface is consistent with a kinetic model taking into account the powder oxygen content, the partial pressure of oxidizing species, and the pore morphology of the sintered material. The presence of silica at the particle surface inhibits coarsening and promotes densification of the powder compact, which is confirmed by kinetic calculations.