Abstract: The study of manganese-substituted barium hexaferrite BaFe12–xMnxO19 with a degree of substitution x from 0 to 2 is presented. The samples are prepared by the solid-phase synthesis at a temperature of 1275 °C and isothermal holding for 5 h. The elemental composition of the samples is determined using energy dispersive spectroscopy, which shows good correspondence with the specified calculated compositions. Monophasicity of all synthesized samples is confirmed by powder X-ray diffraction. In addition, the effect of manganese substitution on the unit cell parameters is estimated. In the differential scanning calorimetry study of the properties, the effect of manganese substitution for iron on the Curie points of the samples obtained, which are caused by changes in the magnetic structures of the produced materials, is determined. The results indicate a significant effect of manganese substitution on the properties of barium hexaferrite and confirm the possibility to control the substitution process for the production of materials with adjustable magnetic characteristics. © Pleiades Publishing, Ltd. 2024.