The internal friction of several compositions of V2O5·P2O5 glasses has been measured in the kHz region from 100° to 400°K. A relaxation peak strongly dependent upon composition exists below room temperature in these glasses. The activation energies of the peaks lie between 0.1 and 0.2 eV. The isotropic elastic moduli and densities were measured for some compositions. These glasses are n-type semiconductors. Direct current electrical conductivities ranged from 6×10−2 to 4×10−6 Ω·cm−1 at 100°C over the composition region studied. The connection between the internal friction and the dc electrical conductivity is discussed.