In this work, coffee husk based activated carbon (CHAC) was prepared by physicochemical activation for the removal of Remazol Brilliant Orange 3R (RBO3R) dye from aqueous solution. The effects of dye initial concentration, contact time, solution temperature and pH on RBO3R adsorption were investigated. Result showed that the adsorption of RBO3R was favorable at acidic pH. The adsorption uptake was found to increase with increase in initial RBO3R concentration, contact time and solution temperature. Langmuir isotherm model fitted well the adsorption equilibrium data with monolayer saturation capacity of 66.76 mg/g at 303 K. The adsorption kinetic was found to follow the pseudo-second-order kinetic model. Boyd plot indicated that the adsorption of RBO3R on CHAC was controlled by film diffusion. The adsorption process was found to be endothermic with the reaction mechanism follows a physisorption process. (C) 2011 Elsevier B.V. All rights reserved.