The title thiazole orange derivative, bearing an alkene substituent, crystallized as a monohydrate of its iodide salt, namely, (Z)-1-(hex-5-en-1-yl)-4-{[3-methyl-2,3-dihydro-1,3-benzothiazol-2-ylidene]methyl}quinolin-1-ium iodide monohydrate, C24H25N2S+·I−·H2O. The packing features aromatic π-stacking and van der Waals interactions. The water molecule of crystallization interacts with the cation and anion via O—H...N and O—H...I hydrogen bonds, respectively.
