2 KBrO3 + 8 KI + 6 H2SO4 → 4 I2 + Br2SO4 + 5 K2SO4 + 6 H2O
This is an oxidation-reduction (redox) reaction:
2 BrV + 12 e- → 2 Br-I (reduction)
SVI - 4 e- → SX (oxidation)
8 I-I - 8 e- → 8 I0 (oxidation)
KBrO3 is an oxidizing agent, H2SO4 is a reducing agent, KI is a reducing agent.