A series of zinc-tellurite oxide glasses based on (25ZnO center dot 75TeO(2))(y)center dot(Ta2O5)(x) (y = (100-x)%) system with different compositions of Ta2O5 (x = 0-7 with increment of 1% mole) have successfully been synthesized by the conventional melt-quenching technique and their structural, optical, thermal and some physical properties were determined. For this purpose, structures of the synthesized glasses were investigated using XRD, FTIR-ATR and DSC. Strong absorption bands that were found within the range of 760 cm(-1) and 570-670 cm(-1) were observed as the stretching vibrations mode of [TeO3] and [TeO4], respectively. Direct and indirect optical band gaps were calculated according to Tauc plot. It is found that addition of Ta2O5 to ZnO-TeO2 glass network increases the glass transition temperature (Tg), crystallization temperature (Tc), thermal stabilities (Delta T) and also density and molar volume. The measured values of electrical conductivity and resistivity using 4 probe method, and changes of the refractive index, have also been examined in this paper.