The study investigates the synthesis and properties of cobalt-doped zinc sulfide (CoxZn1-xS) polycrystalline semiconductors, prepared using a co-precipitation method. Characterization through X-ray diffraction, UV absorption, and other techniques reveals a shift from hexagonal to cubic structure as cobalt concentration increases, along with a decrease in the optical band gap from 3.91 eV to 3.62 eV. The results highlight the potential of these materials for applications in spintronics and photonic devices due to their tunable magnetic and optical properties.