In order to elucidate the effect of europium content on the optical and luminescent properties of borogermanate glasses, a series of Eu 3+ doped 30B 2 O 3 -40GeO 2 -(30-x)Gd 2 O 3 glasses with various doping levels (x=1-9 mol%) have been synthesized and studied with transmission, absorption, photoluminescence and decay time measurements. The transmission spectra proved that the title glasses maintained a high transparency about 80% in the 440 to 900 nm region. Based on the absorption spectra, the optical band gaps obtained from Tauc's plot can be narrowed by increasing content of Eu 3+ . From the photoluminescence spectra, the strongest red emission has been observed from the 5 D 0 → 7 F 2 level of Eu 3+ ions in borogermanate glasses. The strongest emission and excitation intensities of Eu 3+ ions are at the doping level of x=7 mol% and then these intensities decrease due to concentration quenching. The red to orange ratio (R/O) of 5 D 0 → 7 F 2 to 5 D 0 → 7 F 1 transitions has been investigated to predict the local environment of Eu 3+ ions. Judd-Ofelt (J-O) analyses have been performed from the emission spectra. The values of R/O and Ω 2 present an increase with increasing doping level, indicating the lower symmetric environment for Eu 3+ ions and higher covalency for Eu-O bond. The emission efficiency calculated from J-O theory is 75% at x=2 mol%. The decay time curves of 6 P 7/2 → 8 S 7/2 transition of Gd 3+ ions and 5 D 0 -7 F 2 transition of Eu 3+ ions confirm the energy transfer from Gd 3+ to Eu 3+ ions.