Activated carbon prepared from Ricinus communis Pericarp was used to remove Ni(II) from aqueous solution by adsorption. Batch mode adsorption experiments are carried out by varying contact time, metal‐ion concentration, carbon concentration and pH to assess kinetic and equilibrium parameters. The adsorption data were modeled by using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacity (Q_o) calculated from the Langmuir isotherm was 31.15 mg/g of activated carbon at initial pH of 5.0±0.2 for the particle size 125‐250 µm.