A low-cost adsorbent has been prepared by carbonizing citrus fruit peel using o-phosphoric acid as an activating agent and investigation has been made to explore the possibility of this adsorbent for liquid phase adsorptive removal of Methylene Blue (MB), selected as a model dye. Operating parameters for carbonization of citrus fruit peel viz., weight ratio of citrus fruit peel to activating agent, temperature and time of carbonization have been optimized by Response Surface Methodology (RSM) considering decolorizing power of prepared sample as response. The carbonized sample prepared at optimum condition as designated by Design Expert Software is termed as Charred Citrus Fruit Peel (CCFP). Physico-chemical characterization of CCFP is done and the study reveals that BET surface area of CCFP is 526 m(2)/g, which is very much comparable to that of commercial activated carbon. Detailed kinetic and equilibrium studies have been performed for liquid phase adsorption of MB using CCFP. Response Surface Methodology has also been applied to model statistically the adsorptive removal of MB from its aqueous solution in batch process using CCFP and to optimize process variables. Maximum 99.08% removal was achieved during kinetic study in a batch contactor. (C) 2011 Elsevier B.V. All rights reserved.