2-[(E)-2-(4-Chloro-phen-yl)ethen-yl]-1-methylpyridinium iodide monohydrate.

In the title compound, C(14)H(13)ClN(+)·I(-)·H(2)O, the cation is nearly planar and exists in an E configuration; the dihedral angle between the pyridinium and benzene rings is 0.98 (17)°. The cations stack in an anti-parallel manner along the a axis through two π-π inter-actions between the pyridinium and benzene rings [centroid-centroid distances 3.569 (2) and 3.6818 (13) Å, respectively]. The cation, anion and water mol-ecule are linked into a chain along the a axis by weak C-H⋯O and C-H⋯I inter-actions together with O-H⋯I hydrogen bonds and the chains are further connected into a three-dimensional network.