In the lattice of the title compound (systematic name: 5,6,7-trihydroxy-4'-methoxyisoflavone monohydrate), C16H12O6.H2O, the isoflavone molecules are linked into chains through R(4)3(17) motifs composed via O-H...O and C-H...O hydrogen bonds. Centrosymmetric R(4)2(14) motifs assemble the chains into sheets. Hydrogen-bonding and aromatic pi-pi stacking interactions lead to the formation of a three-dimensional network structure.