Manganese(II) sulfate is the inorganic compound with the formula MnSO4. This colourless deliquescent solid is a commercially significant manganese(II) salt. Approximately 260M kg/y were produced worldwide in 2005. It is the precursor to manganese metal and many chemical compounds. Mn-deficient soil is remediated with this salt.
Like many metal sulfates, manganese sulfate forms a variety of hydrates: monohydrate, tetrahydrate, pentahydrate, heptahydrate. The monohydrate is most common. All of these salts are faintly pink. The pale color of Mn(II) salts is characteristic of high-spin complexes with the d5 configuration.
Treatment of manganese sulfate with potassium permanganate affords manganese dioxide, a component of dry-cell batteries.