Mechanical wear resistance of the α- and β- Ga2O3 polymorphs is experimentally studied. We report about tribological cyclic tests of these wide-band-gap semiconductor crystals. To the best of our knowledge, this is the first attempt at considering these crystals as protective coatings. The crystalline layers were deposited on sapphire substrates by vapour-phase epitaxy. This method allows applying coatings on large areas and surfaces of complex shapes, including the surfaces of a number of metals. It has been revealed, that both polymorphs are highly wear-resistant, and suddenly have a very low coefficient of friction. The α- Ga2O3 layers with the corundum structure exhibit wear coefficient values commensurate with those of sapphire and gallium nitride.