[en] N-channel depletion MOSFETs were irradiated with 4 MeV Proton and Co-60 gamma radiation in the dose range of 100 krad(Si) to 100 Mrad(Si). The electrical characteristics of MOSFET such as threshold voltage (V_t_h), density of interface trapped charges (ΔN_i_t), density of oxide trapped charges (ΔN_o_t), transconductance (g_m), mobility (μ), leakage current (I_L) and drain saturation current (I_D _S_a_t) were studied as a function of dose. A considerable increase in ΔN_i_t and ΔN_o_t and decrease in V_t_h_,g_m, μ, and I_D _S_a_t was observed after irradiation. The results of 4 MeV Proton irradiation were compared with that of Co-60 gamma radiation and it is found that the degradation is more for the devices irradiated with 4 MeV Protons when compared with the Co-60 gamma radiation. This indicates that Protons induce more trapped charges in the field oxide region when compared to the gamma radiation.