Powdered strontium and barium hexaborides were obtained by the method of electrochemical synthesis from their molten chlorides with the addition of oxides with the continuous introduction of boron oxide. Their chemical and phase composition, the content of impurities (no more than 2%) and the current efficiency were determined. An atypical formation of hexaborides not on the surface of the cathode, but in the adjacent electrolyte layer, which is observed in melts containing sodium chloride, is explained.