The absorption spectra of the undoped Y 2 SiO 5 and Eu 3+ -doped Y 2 SiO 5 crystals grown by the Czochralski technique were compared before and after annealing and, similarly, the unannealed and annealed crystals after γ-ray irradiation. The absorption bands of Eu 2+ ions with peaks at 300 and 390nm were observed in the as-grown Y 2 SiO 5 :Eu 3+ crystal. These peaks were more intense in H 2 -annealed and irradiated Y 2 SiO 5 :Eu 3+ crystals. The additional absorption peaks at 260 and 320-330nm which were attributed to F color centers and O − hole centers were observed in irradiated undoped Y 2 SiO 5 and Y 2 SiO 5 :Eu 3+ crystals, respectively.