Ultraviolet, visible (UV/VIS) and differential thermal analysis (DTA) measurements were carried out in order to investigate the optical and thermal properties of various 0.5 mol.% Tm 2 O 3 containing (1-x)TeO 2 +xLiCl glasses in molar ratio. The samples were prepared by fusing the mixture of their respective reagent grade powders in a platinum cricuble at 750 o C for 30 min. DTA curves taken in the 23-600 o C temperature range with a heating rate of 10 o C/min reveal a change in the value of the glass transition temperature, T g , while melting was not observed for the glasses containing LiCl content less than 50 mol.%. These glasses were found to be moisture-resistant. However, the glasses with LiCl content higher than 50 mol.%, in which a melting peak was observed at T c =401 o C, were moisture-sensitive. Absorption measurements in the UV/VIS region of the glasses without Tm 2 O 3 content show that the Urbach cutoff occurs at about 320 nm and, is relatively independent of the LiCl content. Six absorption bands were observed in the Tm 2 O 3 doped glasses corresponding to the absorption of the 1 G 4 , 3 F 2 , 3 F 3 and 3 F 4 , 3 H 5 and 3 H 4 levels from the 3 H 6 ground level of Tm 3 + ions. The spectra also show that the integrated absorption cross-section of each band depends on the glass composition. Judd-Ofelt theory was used to determine the Judd-Ofelt parameters as well as the radiative transition probabilities for the metastable levels of Tm 3 + ions in (0.3)LiCl+(0.7) TeO 2 : 0.01 Tm 2 O 3 glass which is moisture-resistant.