The compounds ScMnO3 and CaMnO3 were obtained by high- temperature solid state reactions considering a stoichiometric rate of CaCO3: Mn2O3 and Sc2O3:Mn2O3. The findings were characterized by X-ray powder diffraction. The determination method of average oxidation state of these compounds based on dissolving the samples in concentrated HCl solution. Cl2 obtained by dissolving the samples is reduced by KI solution. I2 was titrated with standard sodium thiosulfate solution. In the calculation it was taken a as a fraction of Mn3+ in the mixed oxides. The formula of Scandium manganite was formulated as ScMnO3+0.12, and for calcium manganite as CaMnO3-0.03. The relative standard deviation in the identification of Mn does not exceed 3,5%.