HNO₃(aq) + HI(aq) → NO(g) + I₂(s)

acidic environment

[HNO₃(aq) + 3 H⁺(aq) + 3 e^– → NO(g) + 2 H₂O(l)] × 2

[2 HI(aq) → I₂(s) + 2 H⁺(aq) + 2e^–] ×3

sum and eliminate common species

2 HNO₃(aq) + 6 HI(aq) → 2 NO(g) + 3 I₂(s) + 4 H₂O(l)