Thermally stimulated luminescence and exoelectron emission (TL and TEE) near the main dosimetric (440 K) "chromium" (550 K) peaks were studied in anion-deficient α - Al2 O3 - δ crystals by methods of modulation thermoactivated spectroscopy with optical and X-ray excitation. Temperature dependences of kinetic parameters of TL and TEE processes were calculated from the obtained results. An anomalous behaviour and overestimated values of the activation energy in the region of main peak were revealed. Possible causes of the observed deviations were discussed. A model of the defect responsible for the TL and TEE peaks near 440 K was proposed.