Abstract New thiohalide glasses have been prepared in four ternary systems Sb 2S 3Hg X 2Pb X 2 (with X = Br, I). The characteristic temperatures ( T g, T c, T f) have been determined. The observed zero-material dispersion wavelength λ 0 (where d 2n dλ 2 = 0 ) and the slope of the refractive index dispersion ( dM dλ at λ 0) have been compared with the calculated values using the concepts of oscillator strength and excitation energy of Wemple. The optical transparency ranges from 0,6 to 14 μm for rich halide glasses. The theoretical optical losses have been estimated; they are quite adapted to utilization in the far-IR. Some other properties, such as chemical stability and hardness, and the dielectric constant are reported.