The phase formation sequence was studied in the preparation of solid solutions of RE₂O₂S: Ln’ (RE = La, Y; Ln’ = Ce, Eu, Dy, Er) by the reduction of the match co-precipitated sulfates, followed by sulfidization of the reduction products. For uniform distribution of cations in the matrix, a method of chemical homogenization was used, consisting in the preparation of an aqueous solution containing all the necessary cations and their subsequent precipitation in the form of sulfates. The use of sulfates as precursors facilitates the process of obtaining solid solutions of oxysulfides, since sulfates already contain SO₄ ^2--ions. The phase and morphological certification of the obtained solid solutions was carried out. The study of steady state luminescent properties demonstrated characteristic bands which are assigned to 4f-4f and 5d-4f transition. The obtained results showed the possibility of applying the method to synthesize optical ceramics based on solid solutionsRE₂O₂S: Ln (RE = La, Y; Ln = Ce, Eu, Dy, Er).