Synthesis of green adsorbent materials for the removal of pollutants is a research priority for sustainable environment. A green hydrogel adsorbent based on graft polymerization of acrylic acid on chitosan was performed using different doses of gamma radiation (5, 10, 15, 20, 30 kGy). The formed hydro-gels were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Gelation percent, swelling in different pH solutions, scanning electron microscopy (SEM). The results indicated the complex formation between chitosan and Polyacrylic acid. The hydrogel exhibit a higher gelation percent with increasing irradiation dose, and a much higher selling ability at alkaline medium. The thermal stability of the hydrogel was found to slightly decrease at 30 kGy. The hydrogel prepared at 20 kGy exhibited the highest thermal stability. The hydro-gels were applied for the removal of Cu2+, Co2+ ions from simulated water solutions, and showed potential results. The electron spin resonance (ESR) measurements to absorbed Cu2+ indicated that the polymer active groups were regarded as strong field ligand on Cu2+.