The experimental IR spectra and DTA curves of the binary semiconducting TeO2-V2O5 glass system containing 0-50 mol% V2O5 have been investigated. The composition dependence of glass transition temperature suggested that the structure of this glass system changes at 20 mol% V2O5. The behavior of the theoretically calculated Poisson's ratio and glass transition temperature have been analyzed in terms of the critical structure parameters of the network. The results showed that, at V2O5 concentration less than or equal to20 mol% the glass continuous tellurite network and Te is 4-coordinated. Beyond 20 mol% V2O5, the network gradually changed to continuous vanadate network by the formation Of VO5-groups in addition to TeO3 trigonal pyramids. The cation-anion bond vibration of V=O bond has been calculated and interpreted on the basis of stretching force constant and reduced mass of the bond. (C) 2002 Elsevier Science B.V. All rights reserved.