Hybrid materials were synthesized by chemical grafting of different compounds (diethylenetriamine DETA, cysteine, alanine and serine) on chitosan/magnetite nanoparticles. The sorbents were characterized by TEM, XRD and FTIR analysis and vibrating sample magnetometry (VSM) before being tested for uranium sorption. The nanometric size of sorbent particles reduces the impact of diffusion resistance and uptake kinetics are quite fast. Sorption isotherms are modeled by the Langmuir equation. The sorption is spontaneous and exothermic. Uranium is desorbed using acidic thiourea and the sorbent can be recycled for at least 4/5 cycles.