Rubidium nitrate is an inorganic compound with the formula RbNO<sub>3</sub>. This alkali metal nitrate salt is a white hygroscopic solid that is highly soluble in water.
In a flame test, RbNO<sub>3</sub> gives a mauve/light purple colour.
RbNO<sub>3</sub> can be prepared either by dissolving rubidium metal, its hydroxide or carbonate in nitric acid.
Rubidium compounds have very few applications. Like caesium nitrate, it is used in infrared radiation optics, in pyrotechnic compositions as a pyrotechnic colorant and as an oxidizer, e.g. in decoys and illumination flares although it is rarely used in fireworks to produce a red-violet colour. It is also used as a raw material for preparation of other rubidium compounds and rubidium metal, for manufacture of catalysts and in scintillation counters.