Pure Zinc oxide (ZnO NPs), Zn0.70Co0.30O and Zn0.50Co0.50O nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure, which was confirmed by the X-ray diffraction studies. The oxidation states of the elements O (1s), Zn (2p), and Co (2p) were confirmed by XPS studies. HRTEM images showed that the particles sizes were approximately 20-40 nm and spherical shape for pure and hexagonal shape both Zn0.70Co0.30O and Zn0.50Co0.50O NPs respectively. The FT-IR spectra confirmed the Zn-O stretching bands range at 421 to 495 cm-1 for ZnO NPs. From the UV–VIS spectroscopic measurements, the excitonic pecks were found around 393, 399 and 396 nm for the respective samples. The photoluminescence measurements revealed that the broad emission composed of five different bands due to zinc and oxygen vacancies.