A microscopic model for low energy electron interaction in alkali halides was used to simulate secondary electron emission from CsI induced by x rays with energies up to 100 keV. The integral ‘‘current’’ and ‘‘pulse’’ yields were calculated as function of the x‐ray energy, CsI convertor thickness, and angle of incidence. We observe a decrease in true low energy (<50 eV) secondary electron yields at increasing x‐ray energies and discuss the effectiveness of CsI convertors coupled to gaseous electron multipliers developed for fast, high resolution x‐ray imaging.