Biodegradable and eco-friendly organic acid, benzene-1,3,5-tri-carboxylic acid (trimesic acid), coated on commercial basic alumina, was used as adsorbent to remove toxic Cu(II) ion from aqueous solution. Adsorbent preparation was optimized and was characterized by SEM, EDX, FT-IR, and powder XRD pattern. Effect of various regulating parameters like reaction pH, adsorbent dose and initial Cu(II) concentration was studied in detail. Adsorption isotherms followed the Langmuir isotherm model and adsorption was thermodynamically favourable. Maximum adsorption capacity (Q(m)) for Cu(II) ion has been achieved as 10.80 mg/g. Detail kinetic study revealed that it followed second-order rate. Desorption of Cu(II) ion and re-usability of the adsorbent was also studied. (C) 2008 Elsevier Inc. All rights reserved.