Thermal deformations of Na₆(UO₂)₂O(MoO₄)₄ were studied by high-temperature powder X-ray diffraction. The compound crystallizes in the triclinic system, space group P $$\bar 1$$, a = 7.636(7), b = 8.163(6), c = 8.746(4) Å, α = 72.32(9)°, β = 79.36(4)°, γ = 65.79(5)°, V = 472.74(4) ų. It is stable in the temperature interval 20-700°C. The thermal expansion coefficients (TECs) are α₁₁ = 25.5 × 10^-6, α₂₂ = 7.8 × 10^-6, and α₃₃ = 1.1 × 10^-6 (°C)^-1. The orientation of the TEC pattern relative to the crystallographic axes is a ₃₃^Z = 45°, a ₃₃^X = 122°, a ₂₂^Z = 59°, and a ₂₂^X = 66°. The anisotropy of the thermal expansion is due to specific features of the crystal structure of the compound.