A novel inorganic-organic hybrid borate, [Al₂(fum)(H₃BO₃)(OH)₄]_n·n(H₃BO₃) (1, H₂fum = fumaric acid), has been synthesized and characterized by single-crystal X-ray diffraction, FTIR and elemental analysis. Crystal data for compound 1: orthorhombic, space group Pnma, a = 14.108(3), b = 6.9412(14), c = 14.995(3) Å, V = 1468.3(5) ų, Z = 4, M_r = 359.72, D_c = 1.627 g/cm³, μ = 0.254 mm^-1, F(000) = 736, the final R = 0.0492 and wR = 0.1650 with I > 2σ(I). In compound 1, each Al^Ⅲ ion is coordinated by six oxygen atoms to adopt a distorted octahedral geometry. Both fumarate anion and the coordinated boric acid act as bidentate bridging ligands to link two neighboring Al^Ⅲ centers simultaneously. Each Al^Ⅲ ion is bridged by two μ₂-hydroxyl ligands to construct an infinite wave-like [Al₂(fum)(H₃BO₃)(OH)₄]_n chain. These one-dimensional chains form hydrogen bonds with free boric acid molecules giving rise to a three-dimensional supramolecular network.