In this paper the influence of electron multiplication in ZnS‐type electroluminescence ac devices is studied in a model where the ZnS layer is free from bulk defects. The holes are assumed to recombine with electrons at the interfaces: The two limiting cases of slow and fast hole‐electron recombination rate are treated in some detail. The kinetic equations for the electric field and the filling level of interface electrons are established then the charge‐voltage characteristics are obtained numerically. An anomalously steep charge‐voltage characteristic may be observed for high multiplication rates and slow recombination. In all cases the field is shown to be delayed relative to the current: This phase relationship is related to bulk ideality and allows for qualitative comparisons with experimental data.