高锰酸盐是高锰酸所形成的盐，含有四面体型的高锰酸根离子—MnO₄，其中锰的氧化态为+7，有强氧化性。高锰酸钾是最重要的高锰酸盐，为紫红色的针状晶体。

酸性溶液中，高锰酸根离子被还原为无色的Mn离子：

碱性溶液中还原，既可得到棕色的MnO₂（锰氧化态为+4），也可得到深绿色的MnO₄（锰氧化态为+6）。

A permanganate is the general name for a chemical compound containing the manganate(VII) ion, (MnO−
4). Because manganese is in the +7 oxidation state, the permanganate(VII) ion is a strong oxidizing agent. The ion has tetrahedral geometry. Permanganate solutions are purple in color and are stable in neutral or slightly alkaline media. The exact chemical reaction is dependent upon the organic contaminants present and the oxidant utilized. For example, trichloroethene (C₂HCl₃) is oxidized by sodium permanganate to form carbon dioxide (CO₂), manganese dioxide (MnO₂), sodium ions (Na), hydronium ions (H), and chloride ions (Cl).