In the title compound, Na(+)·C(6)H(4)IO(3)S(-)·H(2)O, the Na atom is hexa-coordinated by O atoms, forming a two-dimensional sheet-like structure in the bc plane, with the iodo-benzene rings protruding above and below. Na⋯O contact distances are in the range 2.419 (2)-2.7218 (18) Å and O⋯Na⋯O angles are in the range 73.70 (5)-158.64 (7)°. The crystal structure is stabilized by O-H⋯O and C-H⋯O hydrogen bonds and C-H⋯π inter-actions. The I atom is disordered over two positions with occupancies of 0.78 (2) and 0.22 (2).