Abstract: The method of imparting contrast to the surface of an object to be viewed microscopically comprises the steps of introducing the object into a vacuum chamber, connecting the object to the positive pole of a high voltage d.c. source, evacuating the chamber, bombarding the surface of the object with a gas-concentrated electron-ion beam, and feeding into the chamber a gas which reacts chemically with the bombarded object surface. Under the effect of the electron beam and negative or neutralized ions a reaction layer then forms which is characteristic of the component parts of the object material. This layer, after the conclusion of the contrasting process can be observed and evaluated under a microscope.