Light yellow, air-sensitive single-crystals of the rhodium(III) orthoperiodato K₈[Rh(IO₆)₂]OH ⋅ 3H₂O were synthesized starting from Rh₂O₃ and KIO₄. The reaction was carried out in a potassium hydroxide hydroflux with a molar water-base ratio of 1.8 at 200 °C. Single-crystal X-ray diffraction revealed a triclinic crystal structure (space group (Formula presented.)). The most striking feature of the structure is the [Rh(IO₆)₂]⁷⁻ anion, a linear sequence of three face-sharing octahedra. It can be interpreted as a rhodium(III) cation coordinated by two orthoperiodato groups. A water molecule and a hydroxide ion form an associate (H₃O₂)⁻. Together with other water molecules, they connect the [Rh(IO₆)₂]⁷⁻ anions via hydrogen bridges to form layers. Upon heating, the compound first loses its crystal water, then the iodine is gradually reduced before evaporating during the final decomposition step, which results in K_0.63RhO₂. In K₈[Rh(IO₆)₂]OH ⋅ 3H₂O, the unusually short Rh^III−I^VII distance of only 276.38(1) pm should allow direct charge transfer in the [Rh(IO₆)₂]⁷⁻ anion. An electron-poor rhodium cation, accessible from the side, could be the active center in the rhodium-catalyzed oxidation of unsaturated organic molecules by periodate.