Аннотация:In this paper, cases of simultaneous replacement of Ca2+ by Na+ and PO4 3- by SO4 2- are considered. Solid solutions were synthesized by the solid-phase reaction (1-х)∙Са3(РО4)2 +х∙(СаSO4 +Na2SO4 ), where x=0.05; 0.15; 0.25. The synthesized samples were studied by X-ray diffraction and SEM with X-ray spectral microanalysis (XSMA), also the pH of the aqueous phase in contact with the substituted phosphates was measured. The XRD results showed that after substitution, the samples had a Ca3(PO4)2 phase with a partial phase of Na2SO4 and after mixing with phosphoric acid, were obtained mixtures of brushite, monetite and TCP phases. According to the pH measurements of aqueous solutions of β-TCP substituted cements, the values of the medium ranged from 10 to 6.8, which indicates the possible further study of these samples for biological testing and the use of these materials for medicine.