8 Al (s) + 3 KClO4 (s) + 12 H2SO4 (aq) → 3 KCl (aq) + 4 Al2(SO4)3 (aq) + 12 H2O (l)
This is an oxidation-reduction (redox) reaction:
3 ClVII + 24 e- → 3 Cl-I (reduction)
8 Al0 - 24 e- → 8 AlIII (oxidation)
KClO4 is an oxidizing agent, Al is a reducing agent.