3 BrCl (g) + 6 KOH (aq) → KBrO3 (aq) + 2 KBr (aq) + 3 KCl (aq) + 3 H2O (l)
This is an oxidation-reduction (redox) reaction:
2 BrI + 4 e- → 2 Br-I (reduction)
BrI - 4 e- → BrV (oxidation)
BrCl is both an oxidizing and a reducing agent (disproportionation (dismutation)).