Superabsorbent sponge with uniform porous structure was prepared by polyelectrolyte complex (PEC) of polyacrylic acid (PAA) with inorganic polymers, high polymer state polyaluminum chloride (HPSPAC), in combination with freezing-induced phase separation (FIPS). The above superabsorbent sponge was prepared under mild conditions, without strong heat, oxidation, or corrosion, which is an ideal superabsorbent material for drug embedding. Structure analysis and swelling kinetics of the superabsorbent sponge as well as kinetics of the release of the model drug, 4-acetaminophen (AMP), from the sponge were investigated. In addition, effects of the crosslinker HPSPAC, the pH of the solution, and the concentration of NaCl solution on the structure and the swelling property of the sponge and sustained-release kinetics were explored. Further, the relationship between the structure of the superabsorbent sponge and its swelling property as well as sustained drug-release characteristics was investigated. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012