Sodium alginate is a natural anionic polysaccharide obtained from natural and microbial resources. It is also used as a flocculating agent and thickener. It is grafted with polyacrylamide, in the presence of ceric ammonium nitrate (CAN) as an initiator. The graft copolymer (SAG-g-PAM) is again hydrolyzed with some amount of alkali. The flocculation characteristics of hydrolyzed graft copolymer (Hyd SAG-g-PAM) are compared with that of the unhydrolyzed ones, in 5 wt % kaolin and 10 wt % iron ore suspensions. The flocculation characteristics of the hydrolyzed graft copolymer are also compared with those of some of the commercial flocculants. The SAG-g-PAM and Hyd SAG-g-PAM are characterized by IR and intrinsic viscosity measurements. The rheological properties of aqueous solutions of hydrolyzed and unhydrolyzed graft copolymers are measured by Advanced AR-1000 Rheometer. There is drastic enhancement in flocculation and viscosifying characteristics on hydrolysis of the graft copolymers. (C) 2004 Wiley Periodicals, Inc.