In the present work, the effects of glass composition and gamma rays irradiation on the optical and infrared absorption spectra of some selected ternary silicate glasses containing mixed CoO + NiO were studied. Experimental results reveal that the colorless parent undoped ternary silicate glasses show no visible absorption. Upon gamma irradiation, two induced absorption bands are observed in the visible region. Ternary silicate glasses containing mixed CoO + NiO show before irradiation the characteristic bands due to both Co2+ and Ni2+ ions. On progressive irradiation, the UV bands increase in their intensities and shift to longer wavelengths masking the first and second visible bands. The introduction of mixed dopant CoO + NiO shows no effect on the main infrared absorption characteristic bands for silicate chains. Gamma irradiation of the glass increases the intensities of infrared absorption bands at first and the intensities almost stabilized with further irradiation. The experimental results are interpreted assuming that CoO and NiO exist mainly as divalent ions with possible tetra and octahedral coordinations. The optical visible absorption bands of both Co2+ and Ni2+ appeared together and interfere whenever they occupy nearby positions. The induced absorption spectra exhibit the characteristic absorption bands caused by the intrinsic base silicate glass and the respective transition metal ions. The response of the doped glasses to gamma rays irradiation is assumed to be related to the formation and annihilation of the induced color centers with prolonged irradiation. (C) 2003 Elsevier B.V. All rights reserved.