It is pointed out that the electron trapping characteristics (&Dgr;VFB‐Ninjcurve) depend on the pulse frequency and the pulse width of the gate voltage used in avalanche hot electron injection from the Si substrate into the SiO2film, while the generation of the interface states depends very little on those factors. It is shown that those correlations are mainly due to the discharge of trapped electrons during the zero‐bias state between pulses. The experimental results of the discharge of trapped electrons are also described and are explained by means of a modified discharge theory of MNOS structures.