AbstractA novel superabsorbent was prepared by utilizing carboxymethyl starch and carboxymethyl cellulose biocomposites as a grafting backbone. The scheme of the CMS-CMC double backbone structure was speculated. It was proposed that the superabsorbent possesses a three-dimensional network with an interpenetrating structure. The response surface methodology was used to optimize the parameters. Interactions among the most influential variables, i.e., the dosage of CMC, the acrylic acid to acrylamide mass ratio, and the neutralization degree of acrylic acid were estimated. A mathematical model was developed, which fit the experimental results well for all of the response variables. The optimal conditions included 28.8 % of CMC dosage, a 1.6 mass ratio of acrylic acid to acrylamide, and 73.4 % of neutralization degree of acrylic acid to achieve 815.2 g/g of water absorbency.