The thermionic emission of positive alkali ions from zeolites has been investigated in the high‐voltage pulsed regime. Current densities of up to 1 A cm−2have been obtained using 2‐&mgr;s‐long 30‐kV pulses. This is about two orders of magnitude larger than currents obtained in the low‐voltage dc regime. There are two major reasons for this difference. First, the currents have a Schottky‐type dependence on electric field, and second, the current rapidly decays in dc operation. The desorbed ion fluxes are up to a million times larger than those for neutrals for high‐voltage pulses. The ratio of these two fluxes can be described by the Saha‐Langmuir equation. This indicates that the alkali atoms and ions are in thermal equilibrium at the surface of the zeolite.