The possibility of synthesizing an ultrafine powder of gadolinium hexaboride from a chloride-oxide melt by electrochemical deposition of components on an inert cathode has been experimentally proven. Previously, a similar synthesis of borides was carried out in a chloride-fluoride melt, and anhydrous lanthanide fluorides, which are produced industrially by fluorination of oxides, were used as a source of lanthanum ions. Technological advantages of our melt are: exclusion of the intermediate redistribution of oxide fluorination; the possibility of electrolysis in air without an inert atmosphere; the use of the simplest design of the electrolyzer and the minimum set of cheap equipment. All this will significantly reduce the cost of the synthesized borides. All reagents were preliminarily prepared and certified by chemical analysis and X-ray diffraction analysis and were stored in an inert box until the experiment. The optimal parameters of the boride synthesis process were preliminarily determined: temperature and concentrations of B2O3 and Gd2O3 oxides; cathodic current densities in the production of gadolinium borides. The experiment was carried out in an air atmosphere. The simplest electrolyzer design consisted of: an inert molybdenum wire cathode, a graphite anode, and an alundum crucible. First, a cleaning electrolysis was carried out at a current density of 0.3 A/cm2 for 15 minutes to remove residual traces of moisture. The main electrolysis was carried out at a current density of 0.4 A/cm2 for 4 hours, with the replacement of the working electrode with an interval of one hour. The resulting precipitate was washed by decantation in distilled water with acidified hydrochloric acid, then the solid phase was separated by vacuum filtration and dried. The phase composition and morphology of the obtained borides were identified by XRD, and the sizes of crystals and their shapes were determined by SEM. It is shown that during electrolysis, a mixture of two phases GdB6 (cubic system, Pm-3m) and GdB4 (tetragonal system, P4/mbm) is formed on the cathode. Chemical reactions of dissolution of boron and gadolinium oxides in calcium chloride due to interoxide interaction, as well as electrochemical gross reactions of formation of borides on the cathode are proposed.