The phase diagram of the SrO+R 2 O 3 +CuO x system, where R ؍ Ho, was investigated in air. The tie-line relationships of the system were determined. The Sr analog of the high T c superconductor Ba 2 HoCu 3 O 6؉x was not observed in this system. Two ternary phases were found, namely, the 9914+24:: solid solution Sr 14؊x Ho x Cu 24 O 41 and the 99green phase:: SrHo 2 CuO 5 . Holmium was found to substitute for the Sr site in the solid solution Sr 14؊x Ho x Cu 24 O 41 up to the value of x+5. The melting temperature range of this solid solution is from 975 to 10253C, for x ؍ 0 to x ؍ 5, respectively. The green phase is isostructural to its Ba analog, BaHo 2 CuO 5 , and is orthorhombic with space group Pbnm and cell parameters a ؍ 7.0971(13) A s , b ؍ 12.0262(23) A s , and c ؍ 5.5849(12) A s . A comparison of the Ho system with reported systems of R ؍ La, Nd, and Y indicated that a trend exists. The larger the lanthanide ions, the more complicated the phase diagrams, i.e., with a greater number of ternary phases/solid solutions. Despite similar ionic radii between Ho 3؉ and Y 3؉ , the phase diagrams of these two systems are rather di4erent. The green phase SrHo 2 CuO 5 is not stable in the Y system.