Direct methane conversion (DMC) has garnered considerable interest from both industries and academia in recent years due to its great economic potential created by significantly increased price differential between low-cost natural gas (NG) and the derived value-added chemicals. Oxidative coupling of methane (OCM), which transforms CH₄ into ethylene (C₂H₄) with molecular O₂ as the oxidant in a single step, is one of the most studied DMCs. However, a major technical challenge for the OCM process is the difficulty to achieve high CH₄ conversion at high C2 (ethane or ethylene) selectivity. The rudimentary cause for this “tradeoff” behavior is that the products (C₂H₆ or C₂H₄) are chemically more reactive than the reactant (CH₄). To overcome this thermodynamic hurdle, minimizing the oxidizing power of the oxidant or lowering the local oxygen partial pressure is key. In this presentation, we show a CO₂/O₂ co-transport membrane reactor for OCM conversion. The results explicitly show that the permeated O₂ can react preferably with CH₄ as in the conventional OCM to form C₂H₆; the latter then undergoes thermal cracking into C₂H₄ and H₂. The roles of the permeated CO₂ are assumed to be reacting with H₂ via reverse water gas shift (RWGS) reaction to shift the C₂H₆ thermal cracking; another role of CO₂ is assumed to be mitigating coke formation via Boudouard (RB) reaction.