Actinium(III) nitrate is an inorganic compound, actinium salt of nitric acid with the chemical formula Ac(NO<sub>3</sub>)<sub>3</sub>. The compound looks like white substance, readily soluble in water.
Actinium nitrate can be obtained by dissolving actinium or actinium hydroxide in nitric acid.
Actinium(III) nitrate decomposes on heating above 600 ðC:
This salt is used as a source of Ac<sup>3+</sup> ions to obtain insoluble actinium compounds by precipitation from aqueous solutions.