The surface morphology, chemical, optical, and structural response of 1.25 MeV gamma rays irradiation at various doses ranging from 16 to 300 kGy on Kapton polymer samples were studied by using scanning electron microscope (SEM), Fourier Transform Infrared (FTIR), ultraviolet/visible absorption (UV/VIS) and X-ray diffraction (XRD). The morphology study shows the blisters formation on the Kapton polymer surface due to 1.25 MeV gamma rays irradiation at ambient temperature. This observation provides a basis for the quantitative evaluation of FTIR results obtained for thermally stable polymer on the chemical bond deterioration with increasing gamma irradiation. The blistering mechanism is correlated with the internal gases (CO, H(2)) released due to gamma radiation induced damages. The recorded UV-VIS spectrum shows a maximum absorption around the wavelength 540 nm. However, the nature of the spectra does not change due to gamma irradiation but a shift in absorption edge towards the higher wavelength side has been observed with increasing dose. The optical data shows an increase in the calculated band gap at the highest dose. The diffraction pattern of virgin sample shows that polymer is semicrystalline, but due to irradiation, a decrease in the peak intensity and FWHM and an increase in the crystallite size at the highest dose level of 300 kGy have been observed. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2928-2937, 2011