A novel PEG macromonomer with rnethacryloyl and sulfonate group at each chain end was prepared, and new PEG-based hydrogels were prepared by crosslinking polymerization of this PEG macromonomer in the presence of PEG dimethacrylate. Their swelling properties are measured and compared with those of reference hydrogel from methoxy PEG methacrylate to elucidate the effect of the sulfonate end group. The prepared sulfonated PEG hydrogels exhibited water absorbency in the range of 19 similar to 42 g water/g dry-gel depending on the composition. These hydrogels with anionic sulfonate group showed swelling behavior varying with salt type, concentration, and also with pH of aqueous solution. The morphology of the sulfonated PEG gels by SEM showed irregular porous network structure varying with the composition. (C) 2005 Wiley Periodicals, Inc.