Semiconductive oxide glasses in the system V2O5–MnO–TeO2 were prepared, and the mechanism of d.c. conduction was studied. The Seebeck coefficient measurements at temperatures from 375–475 K indicated the glasses to be n-type semiconducting. The d.c. conductivity ranged from 5 × 10−5 to 1.9 × 10−6 S cm−1 at 405 K for V2O5 = 60 mol% and MnO = 0–20 mol%, and decreased with increasing MnO content. The conduction was confirmed to obey the adiabatic small polaron hopping model, and was due to mainly hopping between V-ions in the glasses. The polaron band width J was estimated to be J = 0.10–0.20 eV. The electron–phonon interaction coefficient γp was very large (21–26). The hopping mobility evaluated as 2.3 × 10−7 –2.7 × 10−6 cm2 V−1 s−1 increased with increasing V2O5 content. The estimated carrier concentration was the order of 1019 cm−3. The principal factor determining conductivity was the polaron hopping mobility in these glasses.