Potassium dithioferrate is the inorganic compound with the formula KFeS<sub>2</sub>. It is a purple solid that is insoluble in water. Regarding its chemical structure, the compound consists of infinite chains of edge-shared anionic FeS<sub>4</sub> tetrahedra. Associated with these chains are potassium ions. A related family of one-dimensional materials exists with the formula MFe<sub>2</sub>S<sub>3</sub> (M = K, Rb, Cs). These mixed-valence compounds are represented by the mineral rasvumite, KFe<sub>2</sub>S<sub>3</sub>.
The compound is prepared by heating iron powder, sulfur, and potassium carbonate at 900 ðC. According to the idealized stoichiometry, this reaction is proposed to cogenerate potassium sulfate: