In this study, swelling and selective mercury adsorption behavior of novel radiation cross-linked acrylamide/crotonic acid (AAm/CA) copolymers have been investigated in aqueous mercury (II) ion solutions. Swelling experiments were performed in water and in the solution of mercury (II) ions at 25 degrees C, gravimetrically. The equilibrium swelling (S) values of AAm/CA hydrogels were calculated as 11.00 g fluid (g gel)(-1) (in mercury (II) ion solution)35.90 g fluid (g gel)(-1) (in water). For sorption of mercury (II) ions onto AAm/CA, hydrogels were studied by batch sorption technique at 25 degrees C. Adsorption kinetics of the hydrogel-mercury (II) ion system was investigated and some kinetics parameters were calculated. In the experiments of the adsorption, L2-type (Langmiur type-2) adsorption in the Giles classification system was found. In addition, the influences of mercury (II) ion concentration, irradiation dose and CA content in hydrogels, temperature of medium, and counter ions in the mercury compounds were investigated. Selectivity test of the hydrogel was made in aqueous solution of other metal ions such as copper (II), lead (II), and cadmium (II) ions. AAm/CA hydrogels-sorbed mercury (II) ions from the solution of mercury, while the hydrogel did not sorb any heavy metal ions.