Oxidative coupling of methane (OCM) to produce ethane and ethylene is one of the dream reactions of researchers in catalysis. Despite the extensive efforts over the last three decades, our general understanding on OCM is rather poor due to the complexity arising from the reaction network, and also from the various gradients such as temperature and gaseous concentration present in OCM reactors. This chapter highlights reactions active under OCM conditions and how they are interlinked. Special emphasis is given on space-resolved analytical methodologies as promising key enabling tools towards rational development of catalytic materials and processes for OCM.@en