Potassium pentachloronitridoosmate is an inorganic chemical compound with the formula . It is a true nitride, as the nitrogen atom is bonded directly to the osmium atom, which is itself in the +6 oxidation state.
Potassium pentachloronitridoosmate is a red powder that is easily soluble in water, the solutions of which slowly decompose. It is soluble in HCl, but insoluble in organic solvents, and it decomposes in alkali. It forms prismatic crystals.
The compound is made by reacting potassium osmiamate with cold hydrochloric acid in the presence of potassium chloride.
Ozone can oxidize this compound back to potassium osmiamate. HCl and stannous chloride reduce it to , which is regarded as an amide of potassium hexachloroosmate.