Eighteen compositions of MoO₃-Te at 800 ^°C and seven of each of MoO₃-Cd (at 500 ^°C) and MoO₃-Sb (at 600 ^°C) were heat treated in vacuum-sealed quartz ampules. The phases of the heat-treated compositions were analyzed using x-ray diffraction (XRD) patterns. The interac-tions in the three systems are summarized. Three phases in equilibrium are (1) in the _MoO3-Te system at 800 ^°C, Te, Mo₄O₁₁, TeMo₄O₁₃—(0<x_MoO3< 0 889) and ^_MoO3,Mo₄O₁₁, TeMo₄O₁₃—(0.889 < x_MoO3< 1); (2) in the ^_MoO3-Cd system at 500 ^°C, Cd,MoO₂, CdMoO₄—(0<x_MoO3<0.6667) and ^_MoO3, MoO₂, CdMoO₄—(0.6667 < x_MoO3< 1); and (3) in the MoO₃-Sb system at 600^°C, Sb, MoO₂,Sb₄Mo₁₀O₃₁—(0<x_MoO3< 0.734) and ^_MoO3+ MoO₂+Sb₄Mo₁₀O₃₁(0.734 <x_MoO3< 1). The results lead to onstruction of ternary phase diagrams: Te-^_MoO3-TeMo₄O₁₃,Cd-MoO₃-CdMoO₄, and Sb-oO₃-Sb₄Mo₁₀O₃₁.