A technique is described for measuring the density and energy distribution of surface states at the Si‐SiO2interface in MNOS capacitors. The effects of charge injection into the insulator are taken into account by making use of a fast voltage ramp to monitor the instantaneous values of the surface potential during a quasistatic capacitance‐voltage sweep. The technique has been used to investigate the effect of charges trapped in the nitride on the interface‐state density.