EPR and magnetic susceptibility investigations on the \(x{\text{V}}_{\text{2}} {\text{O}}_{\text{5}} \cdot {\text{(100}} - {\text{x)[2P}}_{\text{2}} {\text{O}}_{\text{5}} \cdot {\text{PbO]}}\) glass system with 0 20 mol %) suggests the increase of the associated ion number coupled by superexchange interactions. This result is consistent with magnetic susceptibility data for >3 mol % where the temperature dependence of magnetic susceptibility is described by the Curie–Weiss type law with a negative paramagnetic Curie temperature. The magnetic susceptibility results allowed the estimation of the V4+/V4+ + V5+ ratio in the sample studied.