Superswelling poly(acrylamide-co-sodium acrylate) hydrogels were prepared by free radical polymerization in aqueous solution of acrylamide (AAm) with sodium acrylate (SA) as comonomer and a multifunctional crosslinker such as trimethylolpropane triacrylate (TMPTA). In the sorption studies, binding of a cationic dye such as Lauths Violet (Thionin, LV) onto chemically crosslinked poly(AAm-co-SA) hydrogels has been investigated. Sorption of LV onto poly(AAm-co-SA) hydrogels was studied by batch sorption technique at 25degreesC. In the experiments of the sorption, C type sorption in the Giles classification system was found. Some binding parameters such as initial binding constant (K-i), equilibrium constant (K), monolayer coverage (n), site-size (u), and maximum fractional occupancy (O) for poly(AAm-co-SA) hydrogels-LV binding system were calculated by using Klotz and Scatchard linearization methods. Finally, the mass of sorbed LV per gram of dry hydrogel (q) was calculated to be 3,9-5,9 mg LV per gram for hydrogels.