High energy and high fluence proton irradiated semi-insulating GaAs has been studied by EBIC, PL mapping, C-V, NTSC, PICTS and p-DLTS. The main defects generated by the irradiation were analyzed. An EL2-like defect was found to be dominant. The generation of this defect annihilates the typical cellular distribution of EL2 in as-grown material. The generated EL2 defects present a different photoquenching behavior than the as-grown EL2 defects.