A8Tl11 (A = alkali metal) compounds have been known since the investigations of Corbett et al. in 1995 and still are matter of current discussions as the compound includes one extra electron referred to the charge of the Tl117− cluster. Attempts to substitute the charge by incorporation of a halide atom succeeded for the lightest homologue of the group, Cs8Ga11Cl, and powder diffraction experiments for the heavier homologues also suggested the formation of analogous compounds. However, X-ray single crystal studies on A8Tl11X to prove this substitution and to provide a deeper insight into the influence on the thallide substructure have not yet been performed, probably due to severe absorption combined with air and moisture sensitivity for this class of compounds. In our contribution we present single crystal X-ray analyses of the new compounds Cs8Tl11Cl0.8, Cs8Tl11Br0.9 and Cs5Rb3Tl11Cl0.5. It is shown that a (partial) incorporation of halide can also be indirectly determined by examination of the Tl-Tl distances for low resolved data sets, e.g., for Cs5.7K2.3Tl11Cl?. Mixed occupied sites by two different alkali metals indicate a dependence on the cesium content, the systems K/Rb–Tl–Br and K/Rb–Tl–Cl only gave rise to the formation of the higher reduced (K/Rb)8Tl11 and the less reduced by-product (K/Rb)15Tl27. We have not been able to prove the formation of halide including thallides in the absence of cesium.