[en] A method of sample preparation for electron-probe microanalysis of non-luminescent substances is suggested. The method permits to extend the scope of materials analyzed by tungsten, molybdenum, vanadium, germanium, etc. For this puprpose, an yttrium or gadolinium layer 0.5-1.5 μm thick is coated on the sample surface in vacuum as polished, then vacuum diffusion annealing is performed for 1-3 hours at 700-900 deg C. The layer is then oxydized in gaseous medium at the temperature of luminescent layer formation and analyzed by the cathode-luminescence method