This study has explored a new source of carbonaceous materials, i.e., sunflower seed husk for the adsorption separation process. Activated carbons were produced from sunflower seed husk using phosphoric acid activation in nitrogen. The properties of activated carbons, i.e., bulk density, ash content, iodine number, surface area and surface functional groups were measured together with copper and chromium adsorption activities. The carbon adsorbed 0.75 mmol Cu²⁺/g carbon and 0.37 mmol Cr⁶⁺/g carbon. The Langmuir model best fitted the copper ion adsorption data, while the Freundlich model best fitted the chromium ion adsorption data. Copper and chromium uptake was directly correlated with the number of groups titrable with the base. The results indicated that the acid-activated sunflower seed husk-based carbons were effective metal ion adsorbents and could potentially replace typical coal-based activated carbons in the treatment of metal contaminated wastewater.