In this study the synthesis and characterization of copper oxide nanoparticles via solid state thermal decomposition of a recently synthesized aqua nitrato copper(II) complex with a tri-dentate Schiff-base ligand (1) as a new precursor are reported. The copper complexes were ob-tained by sonochemical and solvothermal process and characterized by scanning electron mi-croscopy (SEM), X-ray powder diffraction (XRD) and FT-IR spectroscopy. The thermal stability of compound (1) was studied by thermogravimetric analysis (TGA). The amount of initial rea-gents and the role of reaction time on size and morphology of nanostructure compound (1) were studied. CuO nanoparticles were simply synthesized at 500 oC under air atmosphere. The diame-ter of CuO nanoparticles was estimated to be about 200 and 30 nm from copper complex precur-sor obtained by sonochemical and solvothermal methods respectively.