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The transparent glasses with composition 30PbO–10GeO 2 –(60−x)SiO 2 −xNb 2 O 5 (mol%) (0 ≤ x ≤ 2.5) are prepared by conventional melt quenching technique. The amorphous nature of the prepared glasses is characterized by XRD. The spectroscopic studies such as optical absorption, FTIR, Raman spectra were carried out at room temperature on these glasses. Besides this electrical properties, like dielectric constant ε ' , loss tan δ , ac conductivity σ a c etc., were also investigated over a moderately wide range of frequency (10 3 –10 6 Hz) and temperature (30–300 °C). The optical absorption spectrum of the prepared glasses has exhibited absorption bands around 325 nm and 340 nm and these are due to the triplet – singlet electronic transition of Ge 2+ state presents in the glass matrix as conversion of GeO 2 into GeO is much easier rather than SiO 2 . From FTIR spectra of as prepared glasses, it is noticed that the intensity of octahedral NbO 6 structural units is found to increase up to 2 mol% of Nb 2 O 5 there after it is observed to decrease. It is also supported by Raman shift of NbO 6 structural units observed around 650 and 930 cm −1 . The analysis of electrical studies is also revealed that the conductivity of prepared glasses is found to increase gradually up to 2 mol% of Nb 2 O 5 beyond this concentration it is observed to decrease. When the spectroscopic investigations are coupled with electrical studies it is concluded that the glass samples doped with 2 mol% of Nb 2 O 5 are found to exhibit good semiconducting nature among the prepared glasses. Such glasses are suitable for fabrication of solid state devices. [ABSTRACT FROM AUTHOR]