Transparent glasses 20ZnF 2 –40Bi 2 O 3 –(40−x)GeO 2 : xFe 2 O 3 ; 0≤x≤2.5wt% are prepared by melt quenching technique. The amorphous nature of the glass samples is characterized by X-ray diffraction (XRD) and differential thermal analysis (DTA). Spectroscopic studies like optical absorption, FTIR, Raman and dielectric parameters (ε′, loss(tanδ) and σ ac over a wide range of frequency and temperature) of these samples have been carried out. Optical absorption data has revealed that the bismuth radicals, observed in pure sample F 0, are decreased with increase in concentration of Fe 2 O 3 . The optical absorption and ESR studies indicate Fe 2+ and Fe 3+ ions occupy octahedral positions at higher dopant concentrations of Fe 2 O 3 . From FTIR and Raman studies, the coordination of germanium is changed from GeO 4 to GeO 6 with increase in the concentration of Fe 2 O 3 . Dielectric parameters such as dielectric constant ε′, loss tanδ, a.c. conductivity σ ac are found to increase and activation energy for a.c. conduction is decreased, hence depolymerise the glass network with increase of divalent iron ion concentration; which is also confirmed by band gap energy (E g ). Density of defect energy states N(E F ) is explained with quantum mechanical tunnelling (QMT) model.