A study on the removal of hexavalent chromium ions from aqueous solution by using activated carbon prepared from Ricinus communis has been done. In this process, it was carbonised and activated by treating with concentrated sulphuric acid followed by heating for 5?h at 500 degrees C. Batch adsorption experiments are also carried out as a function of pH, contact time, initial concentration of the adsorbate, adsorbent dosage and temperature. The experimental data are fitted well to the Freundlich adsorption isotherm. Thermodynamic parameters such as ?H degrees ?S degrees and ?G degrees are calculated, which indicated that the adsorption is spontaneous and endothermic in nature. Adsorbent used in this study is characterised by FT-IR and SEM before and after the adsorption of Cr(VI). (c) 2011 Canadian Society for Chemical Engineering