Promethium(III) bromide is an inorganic compound, with the chemical formula of PmBr<sub>3</sub>. It is radioactive salt. It is a crystal of the hexagonal crystal system, with the space group of P6<sub>3</sub>/mc (No. 176).
Promethium(III) bromide can be obtained by reacting hydrogen bromide and promethium(III) oxide:
Promethium(III) bromide hydrate cannot be heated to form its anhydrous form. Instead it decomposes in water to form promethium oxybromide: