<p>The ternary oxide system CoO–P₂O₅–Cr₂O₃ is an area of ​​search, among others, for new inorganic pigments or dyes. As a result of the research conducted in this work, concerning phase equilibria in the subsolidus region of this system, a new double phosphate of the formula Co₁₃Cr₄P₁₀O₄₄ was discovered. This compound was obtained by multi-stage heating of a stoichiometric mixture of CoCO₃, Cr₂O₃ and (NH₄)₂HPO₄ in the temperature range of 350–1050&#xa0;°C. Both the calculated crystallographic data and the infrared spectrum indicate that Co₁₃Cr₄P₁₀O₄₄ is not isostructural with Cu₁₃Fe₄V₁₀O₄₄, known from the literature. The new phosphate, in a powder form, has an ash-violet colour. It melts incongruently at 1160&#xa0;°C. The second finding, resulting from our studies, is that the previously known phase, assigned to a precisely defined formula Co₃Cr₄(PO₄)₆, has in fact a range of homogeneity, which can be described as Co_3+1.5xCr_4-x (PO₄)₆ (0 ≤ <i>x</i> &lt; 0.323). The paper also presents the division of the subsolidus region of the CoO–P₂O₅–Cr₂O₃ system into subsidiary subsystems. Investigations by the differential thermal analysis method have shown that almost all of the mixtures of phases coexisting in the solid state in equilibrium have relatively high melting points, i.e. above 1100&#xa0;°C. Therefore, not only the new phosphate Co₁₃Cr₄P₁₀O₄₄ discovered in this work, but also these mixtures can be potentially used for colouring of commercially available middle-temperature ceramic glazes with a glazing temperature of 1050&#xa0;°C.</p>