Electron spin resonance (ESR) and d.c. conductivity measurements have been made on a prepared binary tellurite glass in the temperature range 200-400 K. The d.c, conductivity was found to be temperature dependent and had two regimes. The data were consistent with the small polaron transport mechanism and the polaron activation energy was 0.22 eV. The ESR spectra at high temperatures were characterized by two overlapping lines; a broad line with g = 2.00 and a narrow line with g = 1.967. At temperatures lower than 258 K, the narrow line disappeared and the broad line remained. This suggests that carriers become localized at T < 258 K. At T > 273 K, the conductivity arises from hopping of carriers between cerium sites. It was also found that the reduced valency ratio C (i.e., the ratio of the concentration of Ce 4 + ions to the total Ce ion concentration in the glass) increases with temperature.