The optical absorption (OA) and thermoluminescence of oriented α-Al2O3 crystals colored in aluminum vapor have been studied. Optical absorption measurements of an X-irradiated sample at the orientation E⊥C3 during isochronal annealing revealed mutual transformations of F- and F+-centers within the dosimetric peak from 380 to 500K. The transformations occurred simultaneously with emptying of the electron trap whose OA is at 2.8eV. The predominant F→F+ conversion, which could be explained by delocalization of holes, was observed in the low-temperature part of the peak near 380–440K. From the available experimental data it was inferred that the simultaneous release of electrons and holes in the low-temperature part of the peak facilitated formation of excitons bound on F-type centers. The excitons transferred part of the energy stored in the irradiated crystal to F+- and F−-centers during thermal stimulation, leading to luminescence of these centers.