Glasses with the composition of (1 - x)TeO2 + (x)WO3, where x = 0.15, 0.25 and 0.3 were prepared and, their thermal and absorption measurements were carried out. Differential thermal analysis (DTA) curves taken in the 23-600 degreesC temperature range with a heating rate of 10 degreesC/min reveal a change in the value of the glass transition temperature, T-g, while crystallization was not observed for the glasses containing a WO3 content of more than 15 mol%. All the glasses were found to be moisture-resistant. The absorption bands corresponding to the absorption of the (1)G(4), F-3(2), F-3(3) and F-3(4), H-3(5), and H-3(4) levels from the H-3(6) ground level of the Tm3+ ion were observed in the optical absorption spectra. Integrated absorption cross-sections of each band except that of H-3(5) level was found to vary with the glass composition. Judd-Ofelt analysis was carried out for the samples doped with 1.0 mol% Tm2O3. The Omega (2) parameter shows the strongest dependence on the host composition and it increases with the increasing WO, amount. The value of Omega (4) increases rather slowly while the value of Omega (6) is practically independent of the composition. The strong dependence of the parameter Omega (2) indicates that this parameter is related to the structural change and the symmetry of the local environment of the Tm3+ ions in this glass. (C) 2001 Elsevier Science B.V. All rights reserved.