This work presents the potential of strontium ions removal from aqueous solutions using coconut fiber in raw and treated form with hydrogen peroxide, 1% and 4%, in alkaline conditions. The biosorption experiments were performed in batch mode with 2 mg.L-1 solution of Sr(NO 3) 2 and the influence of the following parameters were studied: contact time and pH. It was also evaluate the biosorption efficiency of the treated coconut fibers in comparison with the raw coconut fiber (RCF). The fibers characterizations before and after treatment and the presence of the Sr 2+ in the fibers were performed by scanning electron microscopy with a detector energy dispersive spectroscopy, diffraction of x-ray spectroscopy, infrared spectroscopy and thermal analysis. Among the studied fibers, the treated coconut fiber with 1% of H 2 O 2 (TCF 1) showed the major biosorption capacity of 3.6 mg.g-1 in the following conditions: 5 mg of biomass at pH 6, 90 minutes of contact time at room temperature. Treated coconut fiber with 4% H 2 O 2 (TCF 2) showed the lowest Sr 2+ ions removal due to degradation of the fibers constituents. For studies of biosorption isotherms, both raw and treated coconut fiber (TCF 1) were fitted better to Langmuir model and the kinetics reaction was of pseudo-second order. The thermodynamic parameters Gibbs free energy (ΔG) and distribution coefficient (K D) were-0.90 kJ.mol-1 and 265.3 L.Kg-1 for RCF and of-7,2 kJ.mol-1 and 824.3L.Kg-1 for TCF 1. These results demonstrated that the TCF 1 has good efficiency for removing Sr 2+ ions in the aqueous chemical waste and is a good alternative in treatment of liquid radioactive wastes containing 90 Sr.