CH4 (g) + O2 (g) → 2 H2 (g) + CO2 (g)
This is an oxidation-reduction (redox) reaction:
C-IV - 8 e- → CIV (oxidation)
4 HI + 4 e- → 4 H0 (reduction)
2 O0 + 4 e- → 2 O-II (reduction)
CH4 is a reducing agent, CH4 is an oxidizing agent, O2 is an oxidizing agent.