Indian cement industry is facing environmental issue of emission of carbon dioxide (CO₂), a greenhouse gas. Blended cements including supplementary cementitious materials are substitute of Portland cement to reduce CO₂ emission. The present paper investigates theappropriateness of copper slag (CS) as supplementary cementitious material. Strength properties and hydration of mixes were determined at different replacement levels of CS with cement. Compressive, flexural and tensile strength of each mix was found out at different curing periods. The hydration of cement was investigated through X-ray diffraction (XRD). The strength test results showed that substitution of up to 20% of CS can significantly replace Portland cement.XRD test results were corresponding to strength test results. The present study encourages the utilization of CS as supplementary cementitious material to make economical and environmentally sustainable blended cement