A new 3D Cd(II) coordination polymer, [Cd2L(phen)(H2O)](n) (1, H4L = terphenyl-2,2',4,4'-tetracarboxylic acid, phen = 1,10-phenanthroline), has been hydrothermally synthesized and characterized by single-crystal X-ray diffraction analysis, elemental analysis, TGA and IR spectroscopy. Complex 1 crystallizes in the monoclinic system, space group P2(1)/c with a = 8.196(2), b = 18.348(5), c = 19.036(5) angstrom, beta = 97.741(5)degrees, V = 2836.6(14) angstrom(3), Z = 4, D-c = 1.933 Mg.m(-3), mu = 1.565 mm(-1), F(000) = 1624, the final R = 0.0356 and wR = 0.0612 for 4990 observed reflections with I > 2 sigma(I). Complex 1 has a 1D chain containing Cd4 structural units, which are linked by 2- and 2'-carboxyl groups of L4- to result in a 3D framework. Additionally, the photoluminescent property of 1 was also studied in the solid state at room temperature.