Electron and sodium ion motion in sodium borosilicate glasses containing Sb 2O 3 has been determined by thermally stimulated polarization and depolarization current (TSPC/TSDC) technique. Whereas a glass containing Sb 2O 3 exhibited a TSPC peak, the peak was absent in a similar glass without Sb 2O 3. The TSPC peak which appeared in TSPC-1 and TSPC-2 was 10 3–10 4 times larger than the TSDC peaks and had an activation energy higher than that of the TSDC peaks and ionic dc conduction. Electron hopping between Sb 5+ and Sb 3+ ion sites is considered responsible for the TSPC peak. All the glasses show two TSDC peaks. The origin of the low temperature TSDC peak is uncertain but the high temperature TSDC peak could be accounted for by the orientation of Na + ions around [BO 4] − groups. Above ∼ 360 K the dc conduction is due to sodium ion motion.