The novel coordination polymer {[Cd(p-CMSP)(Him)(H2O)]·3H2O}n (p-CMSP2-=p-(carboxymethoxy) phenylthioacetate, Him=imidazole) was synthesized by the reaction of Cd(NO3)2, imidazole and p-(carboxymethoxy) phenylthioacetic acid in an aqueous solution, and characterized by elemental analysis, IR, TG and single crystal X-ray diffraction. The crystal structure is of monoclinic, space group P21/c with a=1.144 0(2) nm, b=1.876 7(4) nm, c=0.877 89(18) nm, β=106.31(3)°and V=1.808 9(7) nm3, Z=4, R=0.023 2, wR=0.051 4. Each Cd! atom displays a distorted octahedral coordination geometry, defined by three carboxyl O atoms from different p-CMSP2- ligands, one S atom from thioether, one N atom from imidazole and one water molecule. Adjacent Cd! ions are bridged by p-CMSP2- groups, resulting in a 2D layer structure. The adjacent Cd…Cd distances are 0.4927 nm and 1.144 0 nm. Furthermore, such layers are linked through hydrogen bonds to form supramolecular network. CCDC: 269474.