Perovskite ceramics of modified lead zirconate–titanate (PZT) type have been extensively studied because of their excellent dielectric, electro-optical, piezoelectric and pyroelectric properties. Oxygen ions with 200 keV energy and doses of 1.0 × 10 16 ions/cm 2 were irradiated onto a commercially available modified PZT sample having good pyroelectric properties for use in infrared detectors. Its response was studied in terms of dielectric and pyroelectric properties before and after irradiation; a decrease in dielectric constants ( ε′, ε″) and pyroelectric coefficient is observed. Results are explained on the basis of structural defects such as oxygen vacancies, radiation-induced charges trapped at structural defects and domain dynamics. The material figure-of-merits for their use in infrared sensing devices are calculated and compared with un-irradiated sample.