Manganese(III) fluoride, also known as manganese trifluoride, is a chemical compound. It contains manganese and fluoride ions. The manganese ions are in the +3 oxidation state. Its chemical formula is MnF3. It is a purple-pink powder. It is used to add fluoride ions to other chemical compounds. It is an oxidizing agent. It is made by heating manganese(II) fluoride with fluorine. These are in a solution of hydrofluoric acid. It decomposes to manganese(II) fluoride when heated.