Herein, Co- and Mg-doped CuO nanostructures have been hydrothermally synthesized.  The X-ray diffraction technique has been employed for investigating the phase purity and crystal structure, where formation of a typical single phase monoclinic CuO structure has been confirmed. Sharp and intense diffraction peaks have been observed and indicate to a high degree of crystallinity of the synthesized samples. No indication to any secondary or impurity phases could be observed. Microscopic investigation has been used to figure out the size, shape and surface morphology. Both samples show flakes-like nanostructure, with thickness ranging from 30 to 50 nm and from 40 to 100 nm for Co- and Mg-doped CuO respectively. The dielectric properties of the prepared samples have been investigated and compared through examining the frequency dependence of various dielectric parameters and the electrical behavior has been explained. Also, the conductivity and the dielectric parameters have been studied with variation in temperature.