The kinetics of the supersaturation of self‐interstitials during the thermal oxidation of silicon is reexamined by considering a finite diffusivity of these interstitials. The rate of interstitial generation is assumed to be proportional to the rate of oxidation, and the rate of surface annihilation is assumed to be a first order reaction. The result from an analytical solution shows that within a reasonable oxidation time span, a suitable power‐law kinetics is obtained, with an exponent that falls within the range of most of the reported experimental values.