EN
Photo-ESR and optical absorption measurements were done on annealed neutron irradiated GaP crystals. The position of paramagnetic gallium anti-site level in GaP energy gap has been determined. Additionally, the position of paramagnetic phosphorus antisite level, earlier determined in the paper of Kruger and Alexander, has been confirmed. Moreover, unusual in ESR experiments temperature dependence of phosphorus antisite amplitude in neutron irradiated GaP crystals has been explained.