The thermoelectric power of glasses in the systems V2O5-Sb2O3-TeO2 and V2O5-Bi2O3-TeO2 was measured at temperatures in the range 373-473 K. The glasses in both systems were found to be n-type semiconductors. The Seebeck coefficient, Q, at 473 K was determined as -192 to -151 mu V K-1 for V2O5-Sb2O3-TeO2 glasses, and -391 to -202 mu V K-1 for V2O5-Bi2O3-TeO2 glasses. For these glasses in both systems, Heikes’ formula was satisfied adequately for the relationship between Q and In [C-V/(1 - C-V)] (C-V = V4+/V-total, C-V is the ratio of the concentration of reduced vanadium ions), and discussions confirmed small polaron hopping conduction of the glasses in both systems. Mackenzie’s formula relating to Q and V5+/V4+ was also applicable to the glasses in both systems, and it was concluded that the dominant factor determining Q was C-V.