Superabsorbent hydrogels were prepared from chitin dissolved in lithium chloride and N-methyl-2-pyrrolidinone by esterification crosslinking with 1,2,3,4-butanetetracarboxylic dianhydride (BTCA). The absorbency of the chitin hydrogel was strongly dependent on the ratio of BTCA feed to chitin. The hydrogel prepared at the feed ratio of 5 showed the highest absorbency (345 g/g-polymer), and the hydrogel was composed of 0.65 molecules of BTCA per monomer unit of chitin. The hydrogels exhibited good biodegradability by chitinase with a maximum degradation of 91% within 7 days. This method for obtaining the chitin hydrogel was also applicable to cellulose and chitin mixtures, and 1 : 1 cellulose/chitin hybrid hydrogels could be obtained by the esterification crosslinking of a mixture with a 1 : 1 molar ratio of cellulose and chitin. The optimal BTCA feed ratio of 5 resulted in the cellulose/ chitin hydrogel with the highest water absorbency (329 g/g-polymer), and the hydrogel contained 0.65 molecules of BTCA per polysaccharide monomer unit. In addition, the hybrid hydrogels were degraded by cellulase as well as chitinase.