The title compound, 10‐(4‐hydroxybenzoylamino)‐3,4,6,7,9,10‐hexahydro‐1,8‐(2H,5H)‐acridinedione monohydrate,C20H22N2O4.H2O, consists of partially hydrogenated acridine moiety with one benzoylamino substituent on the central ring. The compound crystallizes in monoclinic system with P21/c space group and the unit cell constants are: a = 11.142(4), b = 12.266(2), c = 13.320(2) Å; β = 91.76(2)° and V = 1819.6(8) Å3.The central ring (B) adopts boat and the outer rings (A and C) adopt sofa conformations. The water molecule takes part in OW‐H...O and N‐H...OW hydrogen bond formation with acridinedione and benzoylamino group. The oxygen atom O1 interacts through O–H...O bond with the hydroxyl group and in a head‐to‐tail link up of molecules that results in the formation of an infinite “supra molecular“ chain.