At room temperature, a new three-dimensional organic-inorganic coordination polymer [Cd(C4H2O4)(C3H4N2)(3)](n)(.)2nH(2)O was synthesized by the reaction of Cd(CH3COO)(2)(.)2H(2)O, imidazole and fumaric acid. It was characterized by EA, IR, TG-DTA and X-ray single-crystal diffraction. It crystallizes in the monoclinic system, space group P2(1)/n with a = 8.980(3), b = 15.803(5), c = 13.415(4) angstrom, a = gamma = 90.00 degrees, beta = 98.450(5)degrees, F(000) = 936, M-r = 466.73, Z = 4, V = 1883.0(10) angstrom(3), D-c = 1.646 g/cm(3), mu(MoK alpha) = 1.201 mm(-1), S = 1.041, the final R = 0.0237 and wR = 0.0469. The crystal structure shows that the cadmium has a distorted octahedral environment with three carboxyl oxygen donors and three imidazole nitrogen donors. Each cadmium atom is linked by a fumatate as bridging ligand to afford a one-dimensional framework, and then an infinite three-dimensional supramolecular network is formed through hydrogen bonding interactions.