The ⁵¹V NMR of the diamagnetic V⁵⁺ and paramagnetic V⁴⁺ ions has been studied in the semiconducting V₂O₅–P₂O₅ glass system. From computer‐simulation studies of the ⁵¹V NMR experimental spectra due to the V⁵⁺ sites, it has been determined that the spectra obtained at the higher spectrometer frequencies can be described by a skewed distribution of powder patterns arising from axially symmetric chemical shifts. The most probable value of the chemical shift distribution

{(Σ}_{‖})_{mp}

of the chemical shift parameter

Σ_{‖}

decreases with increasing V₂O₅ content and

{(Σ}_{⊥})_{mp}

is independent of glass composition. An estimate of the nuclear quadrupole coupling constant of the V⁵⁺ site has been made; it ranges from 1.0 to 1.5 MHz as the V₂O₅ content of the glass is increased. The NMR data are interpreted in terms of two types of VO₅ units in the glass. One is a VO₅ unit similar to that in crystalline V₂O₅ and the other is a VO₅ unit with a PO₄ unit substituted for the apex oxygen. From ESR intensity measurements, the ratio of the fractions of V⁴⁺ and V⁵⁺ ions

{(n}_{4} {/ n}_{5})

present in the glass has been determined as a function of glass composition. There is some evidence to indicate that two V⁴⁺ sites are formed for each PO₄ unit that is substituted for an apex oxygen of a VO₅ unit. The implications of these data for the electrical conductivity of the glasses are discussed.

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