Abstract Lead thioarsenate glasses are promising materials for a number of potential applications in far infrared optics, chemical sensing, nonlinear photonics, etc. Electronic properties of the PbS–As 2 S 3 glasses were studied in the past, however, the relationship between the glass and crystal characteristics have not been established. Here we compare the glass‐forming domain in the pseudo‐binary system obtained by usual melt–quenching and mechanical milling. Macroscopic and electrical glass properties are analyzed in comparison with their crystalline counterparts: PbAs 2 S 4 , Pb 5 As 9 S 18 , and Pb 2 As 2 S 5 , and the annealed glasses yielding glassy/crystalline alloys. Although the primary crystallization phases in glasses are consistent with the phase diagram, the lead local environment seems to be different in glasses and crystals, reflected by their properties and preliminary high‐energy X‐ray diffraction results.