3K3[Co(NO2)6] + 2HNO3 → 5NO + 9KNO2 + 3Co(NO3)2 + H2O
Potassium hexanitrocobaltate(III) react with nitric acid to produce nitric oxide, potassium nitrite, nitrate cobalt(II) and water. Nitric acid - concentrated solution. The reaction takes place in a boiling solution.