Hydrogels were synthetized by radical polymerization using potassium persulfate and sodium bisulfite as redox initiators, acrylic acid, acrylamide and 2-acrylamido-2-methyl propanesulfonic acid as the monomers, and ethylene glycol dimethacrylate as the crosslinking agent. The swelling capacity of the hydrogels was determined in both water and aqueous solutions containing lead ions (1000 mg L^-1 of Pb⁺² at pH values of 4.0 and 5.0, constant ionic strength I= 0.1 M