Manganese selenide (MnSe) is a transition metal chalcogenides (TMC) , which has good magnetic, optical, electrical and transport properties and is widely used in superconductors, photocatalysts, semiconductors, supercapacitors, fuel cells and thermoelectric materials.

Manganese selenide is a p-type semiconductor (Eg = 2.0 ev) with rock salt, wurtzite (WZ) and zinc blende structures. Due to lower band gap of manganese selenide its electrical conductivity is higher than MnO (Eg = ～4.2 ev) and MnS (Eg = 3.2 ev). MnSe exists in the α, β and γ phases, of which the α and β-MnSe phases have a cubic structure, while the γ-MnSe phase has a hexagonal structure. α-phase (rock salt) is the most thermodynamically stable. β-phase is very unstable and can only be present as an impurity, while γ-phase is variable. The crystal structure diagram of MnSe is shown below: