In this study, CdZnS nanoparticles (NPs) with different Zn concentrations were synthesized by chemical precipitation at room temperature. Zn concentration values used were determined as 1%, 2%, 5%, 10%. The photocatalytic properties of these synthesized NPs were investigated to determine the optimum Zn concentration in CdZnS NPs with different Zn concentrations. Thus, the optimum Zn concentration with the best photocatalytic activity was found to be 2% and this sample was named Cd0.98 Zn0.02 S. In the second phase of our study, Cd0.98Zn0.02S NPs with different Ni concentrations were synthesized using the same method. The Ni concentration values used were determined as 1%, 2%, 5%, 10%. By examining the photocatalytic properties of these synthesized NPs, the optimum Ni concentration with the best photocatalytic activity was found to be 0.5% and this sample was named Cd0.975Zn0.02 Ni0.975. Finally, the structural, morphological and optical properties of Cd0.98Zn0.02S and Cd0.975Zn0.02 Ni0.975 NPs were investigated, respectively, after the optimum Zn and Ni concentrations were determined.