Oxidative coupling of methane was studied in a solid oxide fuel cell (SOFC) tube type reactor. La0.85Sr0.15MnO3 /8 mol% Y2O3-ZrO2/La1.8Al0.2O3 (abbreviated as LSM/YSZ/LaAlO) were used as a cathode, electrolyte and anode. The C2 selectivity and the methane conversion were 91.7% and 23.7% at 1273 K, respectively. The kinetic rate expression was proposed with two different oxygen species. The internal resistance of cell could be lumped and estimated by maximum power transfer theorem. The effect of external load was investigated both in experiments and calculations. The proposed modeling agreed well with the experimental results.