In the title chromone-tethered benzohydrazide derivative, C21H20N2O7·H2O, the atoms of the 4H-chromen-4-one segment are essentially coplanar (r.m.s. deviation = 0.0073 Å) with the largest deviation from the mean plane [0.012 (3) Å] being found for the benzene C atom. The dihedral angles between the chromone segment and the hydrazide plane and between the chromone segment and the benzene ring of the tri-meth-oxy-benzene unit are 24.67 (9) and 41.28 (8) Å, respectively. The mol-ecule is connected to the solvent water mol-ecule by O-H⋯O hydrogen bonds and weak C-H⋯O inter-actions. Additional N-H⋯O inter-actions are observed and together they link the mol-ecules into chains forming a two-dimensional network along (011).
Keywords: crystal structure.