The second-order nonlinear optical (NLO) itaconite copolymer was synthesized to study the effect of temperature and time on the electrooptic effect. The aminonitrostilbene chromophore was synthesized to be bound to itaconate polymer backbone. Particularly, two chromophoric groups were present to enhance the dipole moment in one repeating unit of polyitaconate. The resistance and electric potential between the two electrodes were characterized with temperature. The electro-optic signal and coefficient were investigated using the modified reflection technique. The time-resolved study gave much information on how the electro-optic property can be brought about. Temporal stability was also observed at various temperatures, which is around and far below glass transition temperature.