An improved trapping‐detrapping model is presented describing the effect of electron injection into the oxide of metal‐oxide‐silicon devices. The model covers both hot‐electron and tunneling injection. It takes into account the spatial variation of the oxide electric field due to the trapped charge as well as the effect of this variation on the trapping‐detrapping processes. The calculated results agree well with previously reported experimental results such as the field‐dependent steady‐state flatband voltage and the trapped charge centroid.