The sodium uranyl sulfate hydrate, Na 6 (UO 2 )(SO 4 ) 4 (H 2 O) 2 , has been synthesized and the crystal structure has been determined by single-crystal X-ray di4raction. The structure crystallizes in space group P1 , a โซุโฌ 5.5503(5), b โซุโฌ 11.2456(9), and c โซุโฌ 14.256(1) A > , โซุโฌ 91.483(2), โซุโฌ 92.583(2), and โซุโฌ 97.588(2)3, V โซุโฌ 880.6(2) A > 3 , Z โซุโฌ 2, and has been re5ned on the basis of F 2 for all unique data collected with monochromatic MoK X-radiation and a CCD-based detector to an agreement factor (R1) of 3.38%, calculated using 5617 unique observed re6ections ("F o "54 F ). The structure contains a novel uranyl sulfate cluster with composition [(UO 2 )(SO 4 ) 4 ] 6ุ that is composed of a uranyl pentagonal bipyramid and four sulfate tetrahedra. Three sulfate tetrahedra are linked to the uranyl pentagonal bipyramid by the sharing of vertices, and the other shares an equatorial edge of the uranyl pentagonal bipyramid. This is the second structure known to involve the sharing of an edge of a uranyl polyhedron with a tetrahedron containing a hexavalent cation. The uranyl sulfate clusters are linked through bonds to Na cations, and by H bonding.