Novel itaconates having a pyrrolidinonyl moiety, i.e. 4-methyl 1-(2-pyrrolidonylethyl) itaconate (PyEMI) and 1-methyl 4-(2-pyrrolidonylethyl) itaconate (MPyEI) were synthesized by the reaction of 2-N-hydroxyethyl-pyrrolidinone (HEPy) with 4-methyl or 1-methyl itaconyl chloride in the presence of triethylamine. The polymerization of PyEMI and MPyEI were conducted in two ways. By photopolymerization using 2,2-dimethoxy-2-phenylacetophenone as a photosensitizer, P(PyEMI)-A and P(MPyEI) were obtained. By redox polymerization using N,N,N,N-tetra-methylethylenediamine - potassium persulfate as an initiating system, P(PyEMI)-B was obtained. It was found that both polymers exhibit thermoresponsive behavior in water. The thermo-responsive behavior of P(MPyEI) is similar to that of P(PyEMI)-A, however, P(PyEMI)-B is more sensitive to a change in temperature than P(PyEMI)-A. The fluid dynamic diameter of P(PyEMI)-A and P(PyEMI)-B in water were detected by a laser scattering method, and it was shown that the fluid dynamic diameter of the latter is about 5 times that of the former Due to the difference in polymer chain size and shape, the thermo-responsive behavior of P(PyEMI)-B is more sensitive in the same mass concentration. The swelling ratios of PyEMI hydrogels with various amounts of cross-linker at different temperature were determined. The thermo-responsive behavior of the PyEMI hydrogel was compared with that of the P(PyEMI) aqueous solution.