A hydro(solvo)thermal reaction of 1,3-benzenedicarboxylic acid (bdcH2) and CuSO4·5H2O produced a coordination polymer [Cu3(bdcO)2(H2O)2]n 1. The alkoxyl-1,3-benzene- dicarboxylate trianion (bdcO3-) found in the final product was in situ generated by the hydroxy- lation of bdcH2 during the synthesis. Its crystal structure has been determined by X-ray structural analysis. The complex belongs to a monoclinic system, space group P21/c with C16H10Cu3O12, Mr = 584.86, a = 5.0349(3), b = 10.422(1), c = 15.639(1) (A), β= 91.977(2)o, V = 820.1(1) (A)3, Z = 2, Dc = 2.368g/cm3, μ = 3.931 mm―1, λ(MoKα) = 0.71073 (A), F(000) = 578, the final R = 0.0328 and wR = 0.0742 for 1730 observed reflections with I≥2σ(I). The copper atoms show different coordination environments. Each bdcO group is binds to three copper atoms through oxygen atoms of carboxy- lates and deprononated hydroxy group in bridging and chelating fashions, affording a copper atom coordinated by two [Cu2(bdcO)2]2- 'matallo-ligand' to yield an extending zigzagged layer perpen- dicular to the c axis.