tin iv selenide (also known as stannous selenide) is a crystalline compound composed of two-dimensional Se-Sn-Se sheets stacked on top of each other. It is an example of a layered metal dichalcogenide, with an electropositive group (Sn) and an anti-elemental element (Se).

Like other transition metal dichalcogenides, tin iv selenide exhibits the insulating properties characteristic of the III-V family of compounds. It is an interesting material for 2D materials research due to its narrow band-gap semiconductor properties.

Typically, bulk single crystals of tin(IV) selenide are used as sources from which monolayer and few-layer SnSe2 can be prepared by mechanical or liquid exfoliation. Its low price makes it a cost-effective alternative to black phosphorus and other more expensive 3D semiconductor materials.

Tin(IV) selenide is a solid-state compound with no ionic bonding; it forms when tin has oxidation number four and the selenium atom has oxidation state two. The compound is a metal selenide and its synthesis involves heating of a stoichiometric mixture of tin and selenium.

Tin(IV) selenide is an irritating substance when inhaled, and can irritate the eyes and respiratory system. Chronic exposure may lead to tin and selenium poisoning. It has a strong burning sensation. It is also toxic if swallowed and can cause vomiting, headaches, fever, chills, muscular pain, thirst, metallic taste, loss of hair, nails and eyebrows, and kidney, liver and spleen damage.