In this study, poly[(N-vinyl imidazole)-co-(2-dimethylaminoethyl methacrylate)] hydrogels with various mole percentages of monomers were prepared by free radical solution polymerization in aqueous media. N,N'-methylenebisacrylamide and 2,2'-azobisisobutyronitrile were used as cross-linker and initiator, respectively. A Fourier transform infrared spectrophotometer, scanning electron microscope and thermogravimetric analyzer were used for the characterization of the hydrogels. The swelling behavior of the hydrogels in aqueous solution was investigated at pH 6.0 and 25°C. The results showed that swelling characteristics were affected by the 2-dimethylaminoethyl methacrylate content of the copolymeric hydrogel. The swelling degree of hydrogels increased from 4.2 g g -1 to 25.4 g g -1 by increasing the 2-dimethylaminoethyl methacrylate concentration from 0 to 15% with respect to the total moles of the monomers.