Chitosan-graft-polyacrylamide semi-interpenetrating polymer network (IPN) superabsorbent hydrogel was prepared via UV irradiation and N, N-methylene-bis-acrylamide was used as crosslinker. The product was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), and scanning electron microscopy (SEM). The hydrogels were observed to exhibit as much as 2580.2% swelling under optimum reaction conditions. The hydrogel is an efficient selective sorbent for the removal of mercuric ions (Hg(II)) from aqueous solutions. The mercury sorption capacity under non-buffered conditions is achieved around 9.98mmol center dot g(1) (or 2001.8mg (mercury)/g (hydrogel)) via the colorimetric method. The kinetic data were fitted to the pseudo second order model. Furthermore, the influence of pH, hydrogel dose, and initial mercury concentration on adsorption capacity of the semi-IPN hydrogel was evaluated. Also, the isothermal adsorption equilibrium data was described using the Langmuir model. Finally, the mercury loaded hydrogel was regenerated without losing its original activity and stability.