(2E)-N'-[(E)-4-Chloro-benzyl-idene]-3-phenyl-prop-2-enohydrazide monohydrate.

The conformation about each of the imine and ethene bonds in the title hydrazide hydrate, C(16)H(13)ClN(2)O·H(2)O, is E. The hydrazide mol-ecule is approximately planar (r.m.s. deviation of the 20 non-H atoms = 0.172 Å). The most significant twist occurs about the ethene bond [C-C=C-C = 164.1 (5)°] and the dihedral angle formed between the benzene rings is 5.3 (2)°]. In the crystal, the presence of N-H⋯O(w) and O-H⋯O(c) (× 2; w = water and c = carbon-yl) hydrogen bonds leads to a supra-molecular array in the bc plane.