We investigated the ferroelectricity in proton-irradiated flexible Pb(Zr0.52Ti0.48)O-3 (PZT) thick films and their non-volatile memory characteristics. The Ni-Cr metal foil substrate allowed high-quality polycrystalline PZT films with flexible functionality to be fabricated using conventional sol-gel and high-temperature annealing methods. The 10-MeV proton-irradiated PZT film exhibited an almost square polarization-electric field hysteresis curve with saturated (P-s) and remnant (P-r) polarizations of 18.9 and 17.0 mu C/cm(2), respectively; which are slightly lower than as-grown PZT with P-s = 28.7 mu C/cm(2) and P-r = 24.3 mu C/cm(2). The P-r did not decrease even after 1000 cycles of continuous bending and unbending at a bending radius of 2.14 mm and decreased slightly to similar to 80% of its initial value after 10(5) s. Although the P-r decreased to similar to 55% after 10(10 )cycles, the electric polarization remained switchable under positive and negative electric fields. These characteristics suggest that the flexible PZT films could be utilized in non-volatile memory device applications in environments with high doses of proton irradiation, such as those in aeronautics and nuclear power plants.