NCO-terminated polybutadiene based liquid crystalline polyurethane films were irradiated with O 7+ ion beam at various fluences ranging 3 × 10 10 to 1 × 10 12 ions/cm 2 . Significant modifications in the structural, optical and chemical properties have been observed after irradiation. UV-visible spectra show a shift toward the higher wavelength regime after irradiation owing to the decrease in the band gap. FTIR spectra show the formation of NH 2 group and CC bonds. The XRD spectra show the semi-crystalline nature of LCPU and with increasing fluence of irradiation a decrease in crystallinity is observed. However an increase in crystallinity at certain fluence followed by a decrease at the higher fluence of irradiation reveals the presence of secondary radiation induced crystallinity in LCPU.