The effect of 30 MeV Li 3þ ion and 8 MeV electron irradiation on the threshold voltage (V TH ), the voltage shift due to interface trapped charge (DV Nit ), the voltage shift due to oxide trapped charge (DV Not ), the density of interface trapped charge (DN it ), the density of oxide trapped charge (DN ot ) and the drain saturation current (I D Sat ) were studied as a function of fluence. Considerable increase in DN it and DN ot , and decrease in V TH and I D Sat were observed in both types of irradiation. The observed difference in the properties of Li 3þ ion and electron irradiated MOSFETs are interpreted on the basis of energy loss process associated with the type of radiation. The study showed that the 30 MeV Li 3þ ion irradiation produce more damage when compared to the 8 MeV electron irradiation because of the higher electronic energy loss value. High temperature annealing studies showed that trapped charge generated during ion and electron irradiation was annealed out at 500 C.