The partial pressures of Te-2 in equilibrium with Ga1-xTex samples were measured by optical absorption technique from 723 to 1373 K for compositions, x, between 0.333 and 0.612. To establish the relationship between the partial pressure of Te2 and the measured optical absorbance, the calibration runs of a pure Te sample were also conducted to determine the Beer's law constants. The partial pressures of Te, in equilibrium with the GaTe(s) and Ga2Te3(S) compounds, or the so-called three-phase curves, were established, From the partial pressures of Te-2 over the Ga-Te melts, partial molar enthalpy and entropy of mixing for Te were derived and they agree reasonably well with the published data. The activities of Te in the Ga-Te melts were also derived from the measured partial pressures of Te-2. These data agree well with most of the previous results except those determined by Predel et al. [Z. Metallkde. 66 (1975) 268]. The possible reason for the high activity of Te measured by Predel et al. [Z. Metallkde. 66 (1975) 268] for x < 0.60 is discussed. Published by Elsevier Science B.V.