RATIONALE: The structure of AgAsS2 glass, which has a broad range of applications, is still not well understood and asystematic mass spectrometric analysis of AgAsS2 glass is currently not available. Elucidation of the structure should help in the development of this material. METHODS: The AgAsS2 glass was prepared by the melt-quenched technique. Laser desorption ionisation LDI using quadrupole ion trap time-of-flight mass spectrometry QIT-TOFMS was used to follow the generation of AgmAsnSx clusters.The stoichiometry of the clusters generated was determined via collision-induced dissociation CID and modelling of isotopic patterns. The AgAsS2 glass was characterised by transmission electron microscopy TEM,scanning electron microscopy SEM and energy dispersive X-ray EDX spectroscopy. RESULTS: The LDI of AgAsS2 glass leads to the formation of unary Ag+/and As3+ specie s, 38 binary AsnSx,AgmSx,and 98 ternary AgmAsnSx singly charged clusters. The formation of silver-rich nano-grains during AgAsS2 glass synthesis has been identified using TEM analysis and also verified by QIT-TOFMS.CONCLUSIONS: TOFMS was shown to be a useful technique to study the generation of AgmAsnSx clusters. SEM, TEM and EDX analysis proved that the structure of AgAsS2 glass is ‘grain-like’ where grains are either: 1 Silver-rich ‘islands’ Agm, mup to 39 connected by arsenic andor sulfur or arsenic sulfide chains or 2 silver sulfide Ag2Smm =9–20 clusters alsosimilarly inter-connected. This obtained structural information may be useful for the development of ultra-high-densityphase-change storage and memory devices using this kind of glass as a base.