3 MnO2 + KClO3 + 3 KCO3 → 3 CO2 + 3 KMnO4 + KCl
This is an oxidation-reduction (redox) reaction:
3 MnIV - 9 e- → 3 MnVII (oxidation)
3 CV + 3 e- → 3 CIV (reduction)
ClV + 6 e- → Cl-I (reduction)
MnO2 is a reducing agent, KCO3 is an oxidizing agent, KClO3 is an oxidizing agent.