Germanium sulfide is a red-brown powder or black crystals.

[1] It hydrolyzes slowly in moist air but rapidly reacts in water forming Ge(OH)2 and then GeO.

[2] Other methods include reduction in a stream of H2 gas,[2] or with an excess of H3PO2 followed by vacuum sublimation.

[1] It has a layer structure similar to that of black phosphorus.

[2] Molecular GeS in the gas phase has a Ge-S bond length of 201.21 pm.