The development of high-tech industries stimulates the growth of requirements to metal structures and a complex of their main and special properties. The use of pulsed electrical discharges, plasma currents, pulsed electromagnetic fields, and their combined effects to improve the mechanical characteristics of metals and alloys is relevant in connec-tion with the need in replacing traditional energy-intensive technologies of structural materials with more advanced ones. The use of pulsed barrier discharge (PBD) in metal treatment, which generates a low-temperature plasma on the surface of the metal being treated, is a new approach to optimize the mechanical properties of metal materials, which is based on electrophysical processes. In the work, strengthening of structural 25KhGNMT steel as a result of the action of PBD on its surface was studied. The treatment of steel by PBD took place in a discharge device at a voltage incre-ment rate of ≈3•1011V/s. The influence of the duration of PBD treatment on the value of Vickers hardness (HV) of the test samples was studied. The study of the structure of 25KhGNMT steel was carried out by the method of transmission electron microscopy in order to determine its changes as a result of the action of PBD. It was established that HV val-ues after PBD treatment increase from 420 to 500 kg/mm2, which is accompanied by microstructure dispersion, which positively affects the mechanical characteristics of 25KhGNMT steel. References 14, figure 5, table 1.