[en] The calculation of spatial distribution of ionization g(x) was made using the experimental values of free path and the coefficient of inelastic reflection of electrons. The g(x) function was approximated by the Gauss function. The one-dimensional approximated solution used is applicable to substances with the atomic number from 10 up to 80 and in the energy range of bombarding electrons from 0.5 up to 500 keV. Based on the relations obtained the density of generation of electron-hole pairs is also determined