The article presents the results of industrial experiments on the development of technology for the production of contact wire for high-speed railways from alloys of the Cu-Mg system. The structure of the cast workpiece was studied by scanning electron microscopy, element-by-element mapping of the workpiece surface area was performed. The hypothesis about the formation of magnesium oxide deposits on the working surface of the crystallizer graphite bushing as a result of magnesium condensation has been confirmed. Changes have been made to the design of the water-cooled crystallizer for the supply of inert gas. A technological mode of continuous casting has been developed, which makes it possible to obtain high-quality cast billets. A contact wire with a nominal cross section of 100 mm2 was made. The mechanical and electrical properties of the contact wire were tested, the results of which indicate full compliance with the requirements of the state standard. A certificate of conformity for the contact wire was obtained based on the results of certification tests.