Iridium(III) sulfide is the inorganic compound with the formula Ir2S3.

It is an insoluble black solid, prepared by heating a mixture of elemental iridium and sulfur[citation needed].

Crystals can be grown by chemical vapor transport using bromine as the transporting agent.

The structure consists of octahedral and tetrahedral Ir and S centers, respectively.

No close Ir-Ir contacts are observed.