The graft copolymer of kappa-carrageenan and acrylamide was prepared using ceric ammonium nitrate as initiator. Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy were used to characterize the graft copolymer. The grafting parameter was optimized by varying the temperature, exposure time, concentration of monomer, initiator, and polymer. The adsorption of Pb++ ions by the graft copolymer was pH-dependent and maximum adsorption was obtained at pH 5. The adsorption data obeyed Langmuir isotherms, and the adsorption capacity was found to be 19.6 mg/g and the adsorption of Pb++ ions was spontaneous and endothermic.