This manuscript deals with the preparation and detailed physical and structural study of B 2 O 3 -CdO-Al 2 O 3 -PbF 2 glasses reinforced with MoO 3 ions. With the addition of MoO 3 , the density and band gap values decreased while the refractive index increased, con rming the transformation of Mo 6+ ions to Mo 5+ ions and resulting in the generation of NBO's in these glasses. The FTIR spectra revealed the presence of different borate and aluminate units. The FTIR spectra also indicated the conversion of Mo 6+ ions to Mo 5+ ions. The effect of MoO 3 ions on Raman spectra was clearly visible and indicated the conversion of BO 4 to BO 3 units, increasing NBO's which helped to explain the density variation.