The electron transfer, IR, RAMAN and photoelectron spectra and the powder diagrams of Tl₂MoO₂S₂, Tl₂WO₂S₂, Tl₂MoOS₃, TL₂WOS₃, Tl₂MoS₄ und Tl₂WS₄ are reported and discussed. The different methods allow a discussion of the strong polarising effect of the Tl(I) cation on the anions. For the purpose of comparison the photoelectron spectra of the salts TI₃MX₄ (M = V, Nb, Ta ; X = S, Se); TI₂MO₄ (M = Mo, W); Cs₂MX₄ (M = Mo, W ; X = S, Se) and other similar salts were aIso measured.