Magnetic resin particles with magnetite (Fe3O4) core and glycidyl methacrylate/divinylbenzene resin shell were prepared. The core-shell particles obtained were immobilized with ethylenediamine, diethylenetriamine, or tetraethylenepentarnine to give resins with names, R-1, R-2 and R-3, respectively. These resins showed good magnetic properties and could be easily retrieved from their suspensions using an external magnetic field. The uptake values of resins towards Hg(II) were found to be 2.1, 3.2, and 4.8 mmol/g for resins R-1, R-2, and R-3, respectively. The effect of chain length as well as the content of amine sites on the uptake behavior was studied at different temperatures. The values of kinetic and thermodynamic parameters of the uptake process were reported. These values reflected the effective role of amine type and chain length on both the rate of uptake and the maximum capacity of the resins. Moreover, the column studies showed that the longer the amine chain was the shorter was the critical bed height.