Activated carbon was prepared from carbonized carbon of Combretum quadrangulare Kurz as a new feedstock. Activated carbon prepared by physical activation was presented the negative surface charge resulting in high Fe2+ adsorption ability. Fe-modified activated carbon exhibited good efficiency on Cr2O72− adsorption. Adsorptions of Fe2+ and Cr2O72− using prepared adsorbents were fitted for Langmuir isotherm and pseudo-second-order kinetic models. Adsorption processes of Fe2+ and Cr2O72− were spontaneous and endothermic nature.