In the title hemihydrate, 2C 13 H 10 INO 3 S·H 2 O, there are two organic molecules ( A and B ) and one water molecule in the asymmetric unit. The benzene rings are inclined to one another by 77.98 (1)° in A and 79.81 (9)° in B . The A and B molecules are connected through a water molecule via N—H...O and O—H...O hydrogen bonds. In the extended structure, the A molecules are interlinked via two water molecules through O—H...O hydrogen bonds to generate R 4 4 (12) loops. Further, the A and B molecules are linked by N—H...O hydrogen bonds, and thus an [010] chain is formed. Several C—H...O interactions extend the chains into sheet lying parallel to the ab -plane. The sheets are further extended into a three dimensional architecture via a C—H...π interaction.