In the reaction between KMnO4, H2C2O4, and H2SO4, KMnO4 acts as the oxidizing agent.

The balanced chemical equation for the reaction is:

5H2C2O4 + 2KMnO4 + 3H2SO4 → 10CO2 + 2MnSO4 + K2SO4 + 8H2O

In this reaction, KMnO4 undergoes reduction, while H2C2O4 undergoes oxidation.

KMnO4 is reduced from Mn(VII) to Mn(II).

H2C2O4 is oxidized from C(II) to C(IV).

The oxidizing agent is the species that undergoes reduction, which in this case is KMnO4.