In the present Study, chitosan in its more usable bead form has been chemically modified by simple protonation and employed as a most promising defluoridating medium. Protonated chitosan beads (PCB) showed a maximum defluoridation capacity (DC) of 1664mgF(-)/kg whereas raw chitosan beads (CB) possess only 52 mg F-/kg. Sorption process was found to be independent of pH and altered in the presence of other co-existing anions. The sorbents were characterized using FTR and SEM with EDAX analysis. The fluoride sorption oil PCB follows both Freundlich and Langmuir isotherms. Thermodynamic parameters. viz., Delta G degrees, Delta H degrees Delta AS degrees and E-a indicate that the nature of fluoride sorption is spontaneous and endothermic. The sorption process follows pseudo-second-order and intraparticle diffusion kinetic models. 0.1 M HCl was identified as the best eluent. The suitability of PCB has been tested with field samples collected from a nearby fluoride-endemic area. (C) 2008 Elsevier B.V. All rights reserved.