A novel hydrogel based on chitosan was prepared by graft copolymerization of acrylic acid on diamino derivative of chitosan, i.e., 6-amino-6-deoxy-chitosan (6a6dC). This diamino chitosan was grafted with acrylic acid in an aqueous solution in contrast to acetic acid in the conventional method. Hydrogen peroxide/l-ascorbic acid redox system was found to be an efficient initiator system for grafting reaction in an aqueous system at room temperature. The synthesized hydrogel, 6a6dC-g-PAA, was characterized by Fourier transform infrared, thermogravimetric analyses and Scanning electron microscopy (SEM). Thermal studies showed that it is more stable than chitosan and 6-amino-6-deoxy-chitosan. This 6a6dC-g-PAA, also showed an appreciable water absorbing capacity which was attributed to the very porous surface as observed from SEM analysis.