A complex of Cu(II) with 1-(6-hydroxynaphthalen-2-yl) butane-1,3-dione (HNBD) was synthesized and characterized by elemental analysis, IR, UV and TG-DTA techniques. IR spectra as well as UV-visible absorption measurements indicated that Cu(II) ion was coordinated to the HNBD ligand. The TG-DTA curves showed that the thermal decomposition for Cu(II) complex was a three-steps process. At first, the complex had a mass loss of water molecules at temperature below 134°C, then the thermal decomposition of the anhydrous complex was a two-stage process, which corresponded to the loss of two naphthol molecules and the oxidative decomposition of other organic fragments of ligand. The final decomposition product of the complex was CuO.