[en] This report presents the luminescence properties of Tb³⁺-doped oxide glasses with high Gd₂O₃ (25 mol%) concentration under UV and X-ray excitation. The intense green ⁵D₄ → ⁷F_J luminescence is observed with strong luminescence quenching of the ⁵D₃ level due to cross-relaxation process. Energy transfer from Gd³⁺ to Tb³⁺ ions is confirmed by both luminescence spectra and decay measurements. The integral scintillation efficiency obtained for the 0.5 wt% Tb³⁺-doped glass under X-ray excitation is of about 40% of that of the reference Bi₄Ge₃O₁₂ crystal. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)