摘要： The present work deals with the synthesis of cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles as a catalyst. The study is investigating the different factors in obtaining cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles. Photocatalytic degradation studies are carried out for water-soluble eosine blue (EB) dye using cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles in aqueous solution. Different parameters such as initial dye concentration, dose of catalyst, contact time and pH have been studied to optimize reaction conditions. It is observed that photocatalytic degradation is a more effective and faster mode of removing EB dye by cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles than work done before. The optimum conditions for the removal of the EB dye are initial concentration 40 mg/L, photocatalyst dose 0.8 g/L, and pH 7.5. The EDS technique gives the elemental composition of synthesised cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles. The TEM and XRD studies are carried for morphological feature characteristics of synthesized cobalt oxide, and Fe2+- and Ni2+-doped cobalt oxide nanoparticles. Pseudo-first-order kinetic has been investigated for both pure and doped cobalt oxide catalysts. Almost 95% dye degradation has been observed for doped cobalt oxide nanoparticles.