Four hot-electron effects in ZnS Schottky diodes are discussed, namely: the impact excitation of manganese, radiative emission from hot electrons, impurity impact ionisation and band-to-band impact ionisation. The first three effects show a steep rise with field at approximately=4*105 V cm-1 and this is followed by an intermediate-field region where the effects go through a maximum or saturate. At still higher fields between 1.2 and 1.6*106 V cm-1 band-to-band impact ionisation occurs. These effects are discussed in terms of the transfer of electrons to the higher minima of the conduction band. The relevance of these observations to TFEL devices is also discussed.