Detailed characterizations of inorganic glasses via optimized rare earth doping/co-doping are challenging. Tellurite glasses with composition (78-x)TeO2-10Li2O-10MgO-2Nd2O3-xEr2O3, (where x = 0.4 to 2.0 mol%) are prepared by melt-quenching technique. The effects of Er2O3 concentration on the thermal stability and structural properties are examined. The X-ray diffraction pattern confirms the glassy nature of all samples. The temperature of glass transition (Tg), crystallization (Tc), melting (Tm) and the difference (Tc-Tg) are determined by differential thermal analyser (DTA). The values of Tc, Tg and Tm are found to vary in the range of 419-430 °C, 300-345 °C and 885-890 °C, respectively. The glass sample with 0.4 mol% Er2O3 shows highest thermal stability. The FTIR spectra measured in the range of 400 - 4000 cm1 exhibits two major absorption peaks around 1600 - 3600 cm1 and 900 - 1200 cm1 assigned to the stretching vibrational mode of OH and Te-OH respectively. Improvements in the optical and thermal properties due to co-doping may be useful for the development of tellurite glass based photonics.