In recent years, there has been an enormous interest in the study of surfactants for supercritical CO2 (scCO2). One important potential application of these materials is in Enhanced Oil Recovery (EOR), where stabilised CO2 microemulsions are formed by injecting CO2 to oil reservoirs under harsh, high pressure-high temperature (HPHT) conditions. This proposal aims to explore cheaper and more environmental friendly surfactants for CO2 microemulsion formation at HPHT, using branched, low surface energy surfactants. This project is supported by a Sêr Cymru II Welsh Fellowship part-funded by the European Regional Development Fund (ERDF).