4 H2O2 (aq) + Pb (s) + S (s) → PbSO4 (s) + 4 H2O (l)
This is an oxidation-reduction (redox) reaction:
Pb0 - 2 e- → PbII (oxidation)
S0 - 6 e- → SVI (oxidation)
8 O-I + 8 e- → 8 O-II (reduction)
Pb is a reducing agent, S is a reducing agent, H2O2 is an oxidizing agent.