This work presents the biosorption potential of Fennel biomass for the effective removal of Cd(II) ions. The biosorption was maximum (92%) at pH 4.3. Maximum biosorption capacities of Cd(II) at 30, 40 and 50 degrees C temperatures were 21, 24 and 30 mg/g, respectively. The biosorption of Cd(II) was concentration dependent and increases from 0.49 to 9.3 mg/g with increase in concentration from 5 to 100 mg/L. Biosorption follows Freundlich isotherm at 50 degrees C. Mean free energies at different temperatures were in between 7.1 and 11.95 kJ/mol indicating chemical nature of biosorption process. Kinetics studies showed that pseudo-second-order kinetics model was applicable to the data. The process was endothermic and spontaneous, the spontaneity of the process increases with increase in temperature. Regeneration studies showed a decrease in the recovery of Cd(II) from 99.8% to 41.7% in five consecutive cycles. 80% of the Cd(II) in single and multi-metal systems was recovered in 10 mL. Breakthrough and exhaustive capacities of Cd(II) in single metal system were 10 and 40 mg/g. For multi-metal systems in double distilled water the breakthrough and exhaustive capacities of Cd(II) were 2 and 12 mg/g. In saline solution the breakthrough and exhaustive capacities of Cd(II) were 0.8 and 4 mg/g. (C) 2009 Elsevier B. V. All rights reserved.