Semi-interpenetrating polymer network (semi-IPN) composite hydrogels based on polyacrylamide (PAAm) as a matrix and either native potatoes starch (PS) or the hydrolyzed PS-g-PAN copolymer as entrapped polymer have been prepared using N,N-methylenebisacrylamide (BAAm) as cross-linker, ammonium persulfate as radical initiator and N,N,N',N'-tetramethylethylenediamine as accelerator of free-radical polymerization. The composite hydrogels have been characterized by FT-IR and swelling behavior as a function of the cross-linker ratio. The kinetics of Methylene Blue (MB) adsorption on the semi-IPN composite hydrogels has been investigated as a function of the nature of the entrapped polymer in PAAm matrix. Sorption of MB on the composite hydrogels has been well described by the pseudo-first order kinetic model, which support physisorption dominates the adsorption process. The dye adsorption tests up to four adsorption/desorption cycles support the reusability of the composite hydrogels as sorbents for cationic dyes. (C) 2011 Elsevier B.V. All rights reserved.