Here, a novel ternary semi-interpenetrating polymer networks (semi-IPNs) were prepared by introducing poly (ethylene glycol), (PEG) into acrylamide/sodium acrylate, (AAm/SA) hydrogels. Water uptake and dye sorption properties of AAm/SA hydrogels and AAm/SA/PEG semi-IPNs were investigated as a function of chemical composition of the hydrogels. Inclusion of hydrophilic monomer in the acrylamide hydrogels caused high swelling capacity and better absorbency for cationic dye molecules. FTIR spectroscopy was used to identify the presence of different repeating units in the semi-IPNs. For swelling characterization, swelling experiments were performed in water at 25 degrees C, gravimetrically. Some swelling and diffusion characteristics were calculated for different semi-IPNs and hydrogels prepared under various formulations. AAm/SA hydrogels and AAm/SA/PEG semi-IPNs were used in experiments on sorption of water-soluble cationic dye such as Janus Green B'' (JGB). For sorption of JGB, the polymeric systems were studied by batch sorption technique at 25 degrees C. Hydrogels and semi-IPNs developed in this study may serve as a potential device for super water retainer and sorbent for removal of some agents and dye molecules. The utilization of these types of materials, in pharmaceuticals, agriculture, biotechnology, environment, separation, purification, and immobilization makes hydrogels more popular. (c) 2011 Wiley Periodicals, Inc. Adv Polym Techn 32: 141153, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/adv.20245