Na 4[In 8(HPO 4) 14(H 2O) 6]·12(H 2O) (trigonal, Pc1, a = 13.8500(2), c = 18.4930(3) Å, V = 3072.12(4) Å 3, and Z = 2), was prepared directly in its sodium form by hydrothermal methods at 398 K, and its structure solved by single crystal methods. The three-dimensional framework structure consists of a network of InO 6 and InO 5(OH 2) octahedra, and PO 3(OH) tetrahedra forming layers, which are held in position by InO 6 octahedra acting as pillars forming 12-membered ring channels. The extra-framework sodium cations are located at the sides of the 12-rings within this framework structure and are coordinated by framework oxygen atoms and extra-framework water molecules. The structure was solved using room-temperature single-crystal X-ray diffraction data from 1732 observed reflections ( I > 3.0σ( I), R = 0.025, and R w = 0.030).