Activated carbon (AC) prepared from parthenium was used to remove Hg(II) from aqueous solution by adsorption technique under varying conditions of agitation time, metal ion concentration, adsorbent dose and PH. Adsorption equilibrium reached within 165 min for all concentrations studied (10 to 50 mg/L). Adsorption is dependents on solution PH, H g (11) concentration, carbon concentration and contact time. Adsorption followed both Langmuir and Freundlich isotherm models. The adsorption capacity was found to be 10 mg/g of AC at initial PH of 5.0 at 30+2degreesC for tile particle size of 125-250 mum. The percent removal increased with PH from 2 to 6 and remained constant up to PH 10.0.