Cement kiln dust is a by-product of the cement industry composed of particles of feedstock and condensed volatilized inorganic salts. The effect of Cement kiln dust (CKD) on the mechanical properties of ternary blend cement pastes was studied by preparing different mixes using 40%CKD, 10% OPC and 50% of three different pozzolanic material (ground granulated blast furnace slag (GGBFS), metakaolin (MK), and ground clay brick (GCB)). The mechanical properties were tested via the determination of compressive strength, bulk density, total porosity, and chemically combined water content at 3, 7, 28, 90, and 180 days. The hydration products were evaluated using x-ray diffraction analysis. The result indicated that 40%CKD greatly enhances the activation of GGBFS, MK, and GCB. The paste that contains (10% OPC, 40% CKD, and 50% GGBFS) gives the highest compressive strength, while (10% OPC, 40% CKD, and 50% GCB) gives the lowest compressive strength.