EN
The complex impedance spectra Z*(ω) were studied for as-grown and annealed in air Na_{0.5}Bi_{0.5}TiO₃ single crystals. Experimental data showed that annealing significantly increased impedance and led to appearance of low frequency Z* relaxation. The detected relaxation processes were associated with charge transfer within the regions with initial and reduced after annealing concentration of oxygen vacancies.