Conductivity and 204 Tl tracer diffusion measurements have been carried out in the (Tl 2 S) x (GeS) 60 (GeS 2 ) 40−x glassy system, where the Tl 2 S concentration changes between 0≤x≤25. The room temperature dc conductivity increases by 7 orders of magnitude with increasing thallium concentration, ranging between 10 −18 Scm −1 for the 60GeS-40GeS 2 matrix and 10 −11 Scm −1 for Tl 2 S-rich glasses. The activation energy decreases from 1.22 to 0.79eV, respectively. The conductivity and thallium diffusion results reveal that the ionic transport becomes to be predominant at high thallium concentrations (≈15at.% Tl). The thallium ion transport number tTl+ increases from 10 −3 for low cation concentrations to tTl+≅1 for the x=20 sample. The Haven ratio, H R ≈1, indicates uncorrelated ion motion even at rather high thallium concentrations. The obtained results are discussed in comparison with similar (Ag 2 S) x (GeS) 60 (GeS 2 ) 40−x glassy system.