The title thiosemicarbazide derivative, C10H16ClN5S·H2O, crystallized as a monohydrate. The molecule has an E conformation about the azomethine C=N bond that links the methylhydrazine-1-carbothioamide moiety to the imidazole ring. The butyl chain substituent on the imdazole ring is disordered over two sets of sites, with a refined occupancy ratio of 0.509 (9):0.491 (9). In the crystal, molecules are linked by O—H...N and N—H...O hydrogen bonds involving the solvent water molecule, forming chains along the c-axis direction. The chains are linked by O—H...S and N—H...S hydrogen bonds, forming a three-dimensional framework.
