The title compound, C12H18N2O4·H2O, was obtained as a product of the reaction of hydroquinone with n-propanol amine. The compound crystallizes as a monohydrate, integrating water into its hydrogen-bonded network. Each diaminoquinone moiety forms two centrosymmetric 10-membered rings through C=O⋯H—N bonds. The resulting bands along  are interlinked through hydroxy groups and water molecules into three-dimensional network. The chemically equivalent bond lengths in the diaminoquinone moiety exhibit a perceptible discrepancy [e.g. C=O bond lengths differ by 0.016 (2) Å], apparently as a result of asymmetric hydrogen bonding: one O atom serves as an acceptor of one hydrogen bond, whereas the other is an acceptor of two.