[en] Homogeneity ranges of Mo₃Te₄ (the Mo-rich phase in Mo-Te system) and the Te-rich phases (> 62 at % Te) in Cr-Te system were determined using high temperature mass spectrometry. The homogeneity range of Mo₃Te₄ was found to be wider by ^-3 at % Te than that given in the tentative phase diagram. While a new poly telluride phase, CrTesub(4-x), was identified the existing uncertainty about the homogeneity range of CrTe₃, hitherto considered as the most Te-rich phase in Cr-Te system could be resolved. Activities of tellurium across the single phase regions were deduced from p(Te₂) measured as a function of composition of the condensed phase. The different compositions (closely spaced) could be realised in situ due to preferential vaporisation of tellurium from both Mo-Te and Cr-Te alloys. The activities of the metal were computed using Gibbs-Duhem integration only in the case of Mo-Te system. (author). 10 refs., 7 figs