A series of single and mixed oxides of nano CuO-NiO were prepared by thermal decomposition of the NiC2O4.2H2O and/or CuC2O4 precursors which obtained via the reaction between alcoholic metal nitrates and oxalic acid solutions. Thermal behavior of the single and mixed salts has been studied using thermal analysis (TG and DTA). Thermal products were characterized using Fouier transform infrared (FTIR), X-ray diffraction (XRD), Electron microscopy (SEM&TEM), Nitrogen adsorption at -196oC and surface excess oxygen measurements. The results revealed that, pure NiC2O4.2H2O and CuC2O4 decomposed at 355 and 325oC, respectively. Also, it was found that the addition of NiO to CuO brought a significant increase in the degree of crystallinity of the mixed oxides which is accompanying with an increase in their particle size and a decrease in the surface area. Moreover, addition of NiO to CuO, also reduces the amount of surface excess oxygen of CuO due to a synergistic effect.