2 KMnO4 → K2MnO4 + MnO2 + O2
This is an oxidation-reduction (redox) reaction:
MnVII + e- → MnVI (reduction)
MnVII + 3 e- → MnIV (reduction)
2 O-II - 4 e- → 2 O0 (oxidation)
KMnO4 is an oxidizing agent, KMnO4 is an oxidizing agent, KMnO4 is a reducing agent.