K-bimessite type MnO2 (delta-MnO2) nanosheets were synthesized via hydrothermal technique and investigated the influence of proton beam irradiations on their structural and electrochemical properties. The effect of various proton beam irradiation conditions (proton energy and dose) on MnO2 nanosheets were studied using X-ray diffraction, SEM, TEM, UV absorption, X-ray photoelectron spectroscopy and Raman spectral analysis. The proton irradiation displayed considerable structural transformation from delta-MnO2 to alpha-MnO2/delta-MnO2 and the morphology from nanosheets to distorted nanotubes. The electrochemical properties of the samples were analyzed using cyclic voltammetry, galvanostatic charge/discharge test and impedance spectroscopic techniques. The sample showed a comparable improvement in the specific capacitance value up to a certain extent of proton irradiation. The MnO2 nanosheets irradiated with proton energy of 7.8 MeV and dose 10(14) p cm(-2) exhibited a maximum specific capacitance value of 159 Fg(-1). But, the sample irradiated with high proton energy (9.8 MeV) and dose (10(16) p cm(-2)) showed 114 Fg(-1) specific capacitance which is much less than that of unirradiated sample (142 Fg(-1)).