A novel Cu(II) dimer, [CuL](2), has been synthesized by the reaction of H2L and Cu(CH3COO)(2) center dot H2O with a 1:1 mole ratio in the mixed solvents of acetone and methanol, and characterized by elemental analysis, IR, TG-DTA etc., where H2L = 4,4'-Dibromo-2,2'-[ethylenedioxybis(nitrilomethylidyne)]diphenol. The crystal structure was determined by single-crystal X-ray diffraction analysis. In one dimer molecule, the Cu:L is 2:2, and the coordination number of every copper(II) atom is five.