A new three-dimensional interpenetrated CdII–organic framework based on 3,3′-azodibenzoic acid [3,3′-(diazenediyl)dibenzoic acid, H2azdc] and the auxiliary flexible ligand 1,4-bis(1H-imidazol-1-yl)butane (bimb), namely poly[[bis[μ2-1,4-bis(1H-imidazol-1-yl)butane-κ2N3:N3′][μ2-3,3′-(diazenediyl)dibenzoato-κ2O:O′]cadmium(II)] monohydrate], {[Cd(C14H8N2O4)(C10H14N2)2]·H2O}n, (1), was obtained by a typical solution reaction in mixed solvents (water andN,N′-dimethylformamide). Each CdIIcentre is six-coordinated by two O atoms of bis-monodentate bridging carboxylate groups from two azdc2−ligands and by four N atoms from four bimb ligands, forming an octahedral coordination environment. The CdIIions are connected by the bimb ligands, resulting in two-dimensional (4,4) layers, which are further pillared by the azdc2−ligands, affording a threefold interpenetrated three-dimensional α-Po topological framework with the Schläfli symbol 41263. The thermal stability and solid-state fluorescence properties of (1) have been investigated.