The hydrothermal reaction of Cd（OAc）2.H2O with 1,2-benzenedicarboxylate （1,2-BDC）, imidazole and H2O resulted in the formation of a binuclear polymeric Cd（ Ⅱ ） complex {[Cd2（1,2-BDC）2（Im）4].（H2O）}n which was then characterized by elemental analyses and single-crystal X-ray diffraction analysis. The crystal is of monoclinic system, space group P21/c with a = 14.6455（3）, b = 9.3530（2）, c = 23.7838（5）A, β= 106.6290（10）°, Cl12H104CdgN32O36, Mr = 3373.47, V = 3121.64（11）A^3, Dc = 1.795 g/cm^3, F（000） = 1672,μ= 1.428 cm^-1 and Z = 1. The final R = 0.0316 and wR = 0.0687 for 5045 reflections with I 〉 2σ（I）. In the title complex, the two Cd（ Ⅱ） ions are in different coordination environments with distorted octahedral and pengonal bipyramidal geometries, respectively. Two Cd polyhedra are linked together through one μ2-η^1：η^1 and one μ2-η^1：η^1 carboxylate groups from different 1,2-BDC ligands, giving rise to a binuclear Cd（ Ⅱ ） cluster, and such clusters are connected by bridged 1,2-BDC ligands to form a 2-D structure along the c axis. The inter- and intermolecular hydrogen bonds further connect the 2-D structures into a 3-D supramolecular network.
