K4[W(CN)8] + 8HNO3 + KMnO4 → 5K3[W(CN)8] + Mn(NO3)2 + 6KNO3 + 4H2O
Oktacyanotungstate(IV) react with nitric acid and potassium permanganate to produce oktacyanotungstate(V) potassium, manganese(II) nitrate, potassium nitrate and water. Nitric acid - diluted solution.