The oxidative coupling of methane (OCM) process, which uses natural gas as a raw material for ethylene production and has been widely investigated since the 80’s, is an alternative to conventional processes based on naphtha cracking. However, many authors have shown that its viability is hampered by the low yields that can currently be achieved during the OCM reaction. In this work, the performance of the OCM reactor and its impact on the overall OCM plant have been quantified from a techno-economic point of view. It has been proven that a very high ethylene price (above 1500 €/ton C2H4) is obtained with the current OCM technology, which corresponds to a C2 reactor yield of around 15%. The sensitivity analysis of the OCM process has revealed that the best reactor performance does not necessarily imply the lowest ethylene price, but there are instead other factors affecting it. With the simulation of the overall plant it has also been demonstrated that a C2 reactor yield of at least 25–30% is the target to obtain an ethylene cost lower than 1000 €/ton C2H4. Finally, it has been shown that, based on the forecast of costs for natural gas and naphtha, the gap between the ethylene price obtained with conventional technologies and the one obtained with the current OCM state of the art is expected to progressively become smaller, forecasting OCM to be competitive with traditional technologies in around 20 years.