This article reports the cointercalation of acrylic acid (AA) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) in the interlayer region of Mg(2)Al layered double hydroxide (LDH) and the application of this inorganic-organic composite material in the field of water superabsorbent. The monomers of AA and AMPS were cointercalated into galleries of Mg(2)Al-LDH (denoted as AA-AMPS/LDH) with various molar ratios by ion-exchange method, which was confirmed by powder X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), and elemental analysis. The polymer-based superabsorbent was prepared through in situ free-radical aqueous copolymerization of AA and AMPS, with AA-AMPS/LDH as additive, N,N'-methylenebisacrylamide (NMBA) as crosslinker and potassium persulfate (KPS) as initiator. The composition of this poly (AA-co-AMPS)/LDH was demonstrated as a good water superabsorbent. The LDH content, water absorbency, thermal stability, and swelling rate of this superabsorbent were also investigated in detail. Results showed that the incorporation of a 5 wt % AA-AMPS/LDH into polymer matrix increased its water absorbency significantly by 27.7% (in water) and by 51.5% (in 0.9 wt % NaCl solution). (c) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 1661-1668, 2011