The Taguchi method, a robust experimental design, was used for optimization of synthesis of a novel biopolymer-based superabsorbent hydrogel, kappa-carrageenan (kappa-C)-g-acrylic acid (AA)-co-2-acrylamido-2-methyl-propanesulfonic acid (AMPS). The Taguchi method was applied for the experimental and standard 18 orthogonal arrays (OA) with seven factors and three levels for each factor. In the synthesis of the superabsorbent, NN'-methylene bisacrylamide (MBA) as crosslinker, ammonium persulfate (APS) as initiator, monomer ratio (AA/AMPS), kappa-C concentration, Total Monomer, neutralization percent (N-U), and reaction temperature were used as important factors. After analyzing with analysis of variance (ANOVA) results showed that maximum water absorption capability for optimized final product was found to be 1195 g water per one gram of dry hydrogel powder. The proposed mechanism for the grafting and chemically crosslinking reactions was proved with FTIR, SEM, and TGA methods. Furthermore, the absorption capability of the hydrogels towards bivalent metal ions was evaluated. Therefore, the hydrogels may be based-considered as a candidate to develop an efficient bio-film absorbent in water treatment applications. (c) 2007 Wiley Periodicals, Inc.