A simple physical model is presented which gives the capacitance‐voltage characteristics of a metal‐oxide‐semiconductor structure at high measurement frequencies in excellent agreement with the experimental observations. The model is based on the concept that at high frequencies the minority carriers within the inversion region act as `fixed charges' and so do not contribute to the ac variation of charge within the semiconductor. However, their presence determines the size of the depletion region under the given dc bias and hence the space‐charge capacitance.