A novel superabsorbent nanocomposite based on hydrolyzed collagen was synthesized by simultaneously graft copolymerization of 2-acrylamido-2-methylpropane sulfonic acid (AMPS) and acrylamide (AAm). Sodium montmorilonite (Na-MMt) was used as clay. Methylenebisacrylamide (MBA) and ammonium persulfate (APS) were used as crosslinker and initiator, respectively. The effect of reaction variables such as nanoclay content, MBA and APS concentrations as well as the AMPS/AAm weight ratio on the water absorbency of nanocomposites was investigated. Although the water absorbency was decreased by increasing of MBA concentration, an optimum swelling capacity was achieved for clay, APS, and AMPS/AAm variables. The structure of nanocomposite was identified using FTIR spectroscopy, XRD patterns, and scanning electron microscopy graphs. The effect of swelling media comprising various dissolved salts and different pHs was studied. Also, water retention capacity was studied, and the results showed that inclusion of Na-MMt nanoclay causes an increase in water retention under heating. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 1170-1179, 2011