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The pentahydrated uranyl orthovanadate (UO₂)₃(VO₄)₂·5H₂O was synthesized in shaken aqueous solution at 60°C, by reaction of UO₃ or a uranyl salt (acetate or nitrate) and V₂O₅. Single crystals were obtained by hydrothermal reaction at 180°C. It crystallizes in an orthorhombic system, space group Cmcm, with a=17.978(2) Å, b=13.561(2) Å, c=7.163(1) Å, V=1746.3 ų, Z=4, ρ_cal=4.3 g·cm⁻³. The structure has been refined to R=0.048 and Rw=0.047 using 1020 independent reflections with I>3σ(I) collected on a Philips PW 1100 automated diffractometer using MoKα radiation. Uranyl ions have two distinct functions. U(1)O²⁺₂ uranyl ions are surrounded in an equatorial plane by five oxygen atoms of four different VO₄ tetrahedra which form pentagonal UO₇ bipyramids. The linkage of UO₇ bipyramids and VO₄ tetrahedra leads to (UVO₆)_∞ layers parallel to the (100) plane. The connection between these sheets is …