Samarium(III) bromide is a dark brown powder at room temperature.

[4] The compound has a crystal structure isotypic to that of plutonium(III) bromide.

[5][6] SmBr3·6H2O can be crystallized by dissolving samarium oxide in 40% hydrobromic acid.

The hydrate and ammonium bromide are heated in a vacuum to obtain the anhydrous form of samarium(III) bromide.

[2] Samarium(III) bromide forms some compounds with hydrazine, such as SmBr3·3N2H4·H2O which is a pale yellow needle-shaped crystal that is soluble in water and ethanol but insoluble in benzene, with d20 °C = 3.147 g/cm3.