Promethium(III) bromide is an inorganic compound, with the chemical formula of PmBr3.

It is radioactive salt.

It is a crystal of the hexagonal crystal system, with the space group of P63/mc (No.

Promethium(III) bromide can be obtained by reacting hydrogen bromide and promethium(III) oxide:[2] Promethium(III) bromide hydrate cannot be heated to form its anhydrous form.

Instead it decomposes in water to form promethium oxybromide:[3]