The title compound, Ni(H2btc)2(hmta)2(H2O) (C30H35N8NiO13), has been syn- thesized by the reaction of Ni(CH3COO)2(H2O, 1,3,5-benzenetricarboxylate and hexame-thylene- tetramine in DMF and characterized by X-ray single-crystal diffraction.It crystallizes in the orthor- hombic system, space group Pccn with a = 20.610(4), b = 12.246(2), c = 12.907(3) (A), V = 3257(1) (A)3, Z = 4, Mr = 774.37, F(000) = 1612, Dc = 1.579 g/cm3 and μ(MoKα) = 0.677 mm(1.The structure was refined to the final R = 0.0476 and wR = 0.1115 for 3221 observed reflections (I > 2σ(I)).Ni(II) ion is penta-coordinated with two oxygen atoms of monodentate carboxylate groups from two 1,3,5- benzenetricarboxylates, two nitrogen atoms from two hexamethylenetetramines in the equatorial plane, and one water molecule in the axial position.The coordination geometry of Ni(II) can be described as a nearly ideal square-pyramid.Hydrogen bonds exist between the complex molecules, leading to a two-dimensional structure.