In water, a copper( II) complex with 2-oxo-propionic acid salicyloyl hydrazone and imidazole Cu(C10-H8 N2O4)(C3H4N2 )(H2O) [C10- H8 N2O42- is the dinegative ion of 2-oxo-propionic acid salicyloyl hydrazone, C3H4N2 is imidazole] has been synthesized. The dark-green crystals of the complex were obtained in methanol, and the crystal structure was determined by single crystal X-ray diffraction analysis. The results show that the complex is monoclinic of space group P2(l)/c, the cell parameters are as follows: a = 1.50583(5) nm, h = 1.08411(3) mn, c = 0.94366(2) nm, α=90°, β= 101.5583(11)°, γ= 90°, F= 1. 50927(7) nm3, Z = 4, μ= 1.479 mm-1, Dc = 1.628 Mg/m3, F((XK)) =756.00, R = 0.0340, ωR=0.0777, GOF = 1.025. In the complex, Cu atom is square- pyramidally coordinated by carboxyl monodentate ligand, one N atom of hydrazone C =N and one O atom of carbonyl of 2-oxo-propionic acid salicyloyl hydrazone, one N atom of imidazole, these four atoms are located at the bottom of the square-pyramid, the other coordinating atom is O atom of H2O locating at the apical position. In the crystal, there are hydrogen bonds either in or between the molecules. The thermal decomposition for the complex was studied and the apparent activation energy was obtained by the Kissinger formulae.

Key words: COPPER COMPLEX, GLYOXALINE, METHYLACETIC ACID P, HYDRAZONE P, CRYSTAL STRUCTURE, THERMAL DECOMPOSITION, ACTIVATION ENERGY, COPPER SULFATE