An analogue of the popular surfactant AOT with isopropyl glycol tails (IG-AOT, Figure.1) has been recently designed as a co-surfactant for water-in-CO2 (w/c) systems: stable microemulsions are formed by mixing IG-AOT with a fluorinated surfactant nFG(EO)2 up to a significant water/surfactant molar ratio w=30. In a preliminary ISIS SANS experiment confirmed formation of elongated micelles at different pressures (Figure 2). Hence, since there are only few reports of similar systems in the literature , this new IG-AOT system deserves further study. Here, experiments are proposed to investigate the structure of IGAOTw/c microemulsions under a range of conditions, and therefore, the ability to act as a liquid CO2 viscosity modifier can be evaluated.