Photoconductivity spectra taken on fast‐neutron‐irradiated samples of GaAs show a structure which is interpreted as being due to transitions between energy levels and either the valence or the conduction band. Levels lie at approximately 0.2‐ and 0.7‐eV above the valence band and 0.5‐eV below the conduction band. Slow‐neutron irradiation has been employed to compensate the acceptor impurity inp‐type GaAs. A level atEv+0.7 eV is detected in the high‐resistivity material thus obtained. It is concluded that such level is associated with a defect that is present in GaAs before irradiation in an inactive form.