Electron Paramagnetic Resonance (EPR) provides a useful tool not only as a probe of local structure and short range order in glasses, but also of magnetic interactions in the glasses containing suitable magnetic ions. We have analyzed the spectra of xFe(2)O(3)center dot(100 - x)[P2O5 center dot Li2O] and x(Fe2O3 center dot V2O5)center dot(100 - x) [P2O5 center dot Li2O] glass systems, with 0 < x <= 50 mol %. [P2O5 center dot Li2O) stands for 50Li(2)O center dot 50P(2)O(5) glass composition. For samples x > 50 mol % a study indicates the presence of crystalline alpha Fe2O3 in the glasses. Observed spectra have resonance lines centered at g similar to 4.3 and g similar to 2.0 typical for Fe3+ and V4+ ions present in the oxide glasses. For low contend of transition metal (TM) oxides (Fe2O3 or V2O5 center dot Fe2O3) the spectra present a hyperfine structure typical for isolated V4+ ions. With the increasing of TM content, the EPR absorption signal showing hyperfine structure superposed by a broad line without hyperfine structure characteristic for clustered ions. At high TM content, the vanadium hyperfine structure disappears and only the broad line can be observed in the spectra. (c) 2012 Elsevier B.V. All rights reserved.