This proposal aims to explore a cheaper and more environmental-benign surfactant system for yielding efficient water/CO2 microemulsions. The new surfactants permit high stability at high water-to-surfactant molar ratios (W0), and mild pressures (P) and temperatures (T). For W/CO2 microemulsions most hydrocarbon (HC) surfactants cannot solubilize water at W0 values above 10, even at high P and T. For any potential industrial applications, not only a high solubilizing power but also mild conditions P (~100 bar) and T (~rt.) will be needed. Our groups in Bristol and Hirosaki (Japan) have been developing new, very promising surfactants for W/CO2 microemulsions.