The promising radiation technology was inculcated for the enhancement of gas sensing performance of fibre optic gas sensor. Magnesium tetraborate (MTB), known for its radiation dosimetry and frequency conversion application was used as a sensor element. Solid state sintering technique was adopted for the preparation of polycrystalline samples. In order to understand the role of crystallinity in gas sensing property, the glasses of magnesium tetraborate was synthesize by following melting-quenching method. Cerium (Ce) was doped with MTB in 0.25 mol% concentration. XRD pattern reveals the perfect incorporation of dopant without changing the crystal structure of the host and the cell parameters are matches well with standard ICDD data (031-0787). UV–Vis absorption spectra show the lack of any strong absorption in visible region. Irrespective of crystalline nature, the gas sensitivity of pristine MTB is highly negligible say, 2 counts/50 ppm and 1 counts/50 ppm respectively. Interestingly, gamma radiation treated MTB:Ce samples shows excellent sensitivity of 35 counts/50 ppm and 46 counts/50 ppm towards acetone vapours. Based on the obtained results, gamma irradiated cerium doped MTB glass is suggested as a best sensor for the detection of acetone with high sensitivity. © 2019 Elsevier Inc.