The article discusses the results of developing required for implementing electrolytic-plasma polishing of parts made from steel, copper and copper based alloys. It also describes the basic principles of engineering that enable determining the criteria for using the proposed technology in the manufacturing industry to solve specific problems related to improving the surface quality during production of crucial parts. The relevance of the presented research is confirmed by the practical outcomes. By using designed equipment and specialized devices, the basic criteria for electrolytic-plasma polishing have been determined according to several schemes. In addition, a range of technological modes has been identified that allows for finishing the surfaces of crucial parts with various geometric configurations. Equations for calculating rational values of basic parameters of proposed technology are presented, as well as graphs showing the dependence of target parameter of surface roughness on main variables of electrolytic-plasma polishing.