MnO₄^–(aq) + H₂C₂O₄(aq) → Mn²⁺(aq) + CO₂(g)

acidic environment

[MnO₄^–(aq) + 8 H⁺(aq) + 5 e^– → Mn²⁺(aq) + 4 H₂O(l)] × 2

[H₂C₂O₄(aq) → 2 CO₂(g) + 2 H⁺(aq) + 2 e^–]× 5

sum and eliminate common species

2 MnO₄^–(aq) + 5 H₂C₂O₄(aq) + 6 H⁺(aq) → 2 Mn²⁺(aq) + 10 CO₂(g) + 8 H₂O(l)