xV(2)O(5)center dot(100 - x)[0.7P(2)O(5)center dot 0.3CaO] glass system was obtained for 0 a parts per thousand currency sign x a parts per thousand currency sign 35 mol% V2O5. In order to obtain information regarding their structure, several techniques such as X-Ray diffraction, FT-IR, and EPR spectroscopies were used. X-Ray diffraction patterns of investigated samples are characteristic of vitreous solids. FT-IR spectra of 0.7P(2)O(5)center dot 0.3CaO glass matrix and its deconvolution show the presence in the glass structure of all structural units characteristic to P2O5. Their number are increasing for x a parts per thousand currency sign 3 mol% V2O5 then, for higher content of vanadium ions, the number of phosphate structural units are decreasing leading to a depolymerization of the structure. The structural units characteristic to V2O5 were not evidenced but their contribution to the glass structure can be clearly observed. EPR revealed a well resolved hyperfine structure (hfs) typical for vanadyl ions in a C-4v symmetry for x a parts per thousand currency sign 3 mol% V2O5. For 5 < x < 20 mol% V2O5 the spectra show a superposition of two EPR signals one due to a hfs structure and another consisting of a broad line typical for associated V4+-V4+ ions. For x a parts per thousand yen 20 mol% V2O5 only the broad line can be observed. The composition dependence of the line-width suggests the presence of dipole-dipole interaction between vanadium ions up to x a parts per thousand currency sign 5 mol% V2O5 and superexchange interactions between vanadium ions for x > 5 mol% V2O5.