Photo-induced graft copolymerization of Sodium Salt of Partially Carboxymethylated Sodium Alginate (Na-PCMSA, DS = 1.10) with methyl methacrylate (MMA) using ceric ammonium nitrate (CAN) as a photo-initiator was carried out under nitrogen atmosphere in an aqueous medium. The reaction conditions for maximum photo-grafting were optimized by varying the reaction time, temperature, amount of substrate, concentrations of nitric acid, photo-initiator (CAN) and monomer (MMA) to study their influence on grafting yields. The optimal reaction conditions were obtained with amount of Na-PCMSA 0.4g (dry basis), CAN concentration of 4 x 10-3 mol/L, HNO3 concentration of 0.3 mol/L, MMA concentration of 0.152 mol/L, reaction time of 4h and reaction temperature of 30oC. Under the optimum reaction conditions, the maximum grafting yields achieved were %G = 284.12 and %GE = 98.44. The characterization of grafted products by means of FTIR, thermal analysis and scanning electron microscopy provided the evidence of photo-grafting of poly(methyl methacrylate) onto Na-PCMSA. The synthesized novel graft copolymer, Na-PCMSA-g-PMMA, may find its potential applications as a metal adsorbent.