The capacitance-voltage (C-V) characteristic is calculated for p-type In0.53Ga0.47As metal-oxide-semiconductor (MOS) structures based on a self-consistent Poisson–Schrödinger solution. For strong inversion, charge quantization leads to occupation of the satellite valleys which appears as a sharp increase in the capacitance toward the oxide capacitance. The results indicate that the charge quantization, even in the absence of interface defects (Dit), is a contributing factor to the experimental observation of an almost symmetric C-V response for In0.53Ga0.47As MOS structures. In addition, nonparabolic corrections are shown to enhance the depopulation of the Γ valley, shifting the capacitance increase to lower inversion charge densities.