Cement industry account for 5-8% of worldwide CO₂ emission. To reduce the environmental impact of cement industries metakaolin and other pozzolanic materials are used to replace part of cement. In this study, metakaolin was obtained from local source. Slump test of the different concrete mixes conducted to explore the effect of incorporating metakaolin on fresh concrete properties. Compressive strength test, splitting tensile strength test and flexural strength test conducted to investigate the effect on hardened concrete properties, to find the optimum cement replacement ratio by metakaolin and to compare with silica fume. The experimental results showed that the use of metakaolin enhanced the workability of the fresh concrete, enhanced the hardened concrete mechanical properties compared to control mix and nearly the same as silica fume mix. The optimum replacement level was 15%, the enhancing in the concrete compressive strength was 10%, the reduction in the CO₂ emissions was 12.38%, and the energy saving was 5.56%, compared to that control mix. Keywords: concrete, metakaolin, silica fume, compressive strength, tensile splitting strength, flexure strength