Spherical reverse micelles have been formed previously in water-in-sc-carbon dioxide (w/c) microemulsions through the use of a special partially fluorinated hybrid surfactant3 (figure 1, b-d). The inclusion of hydrotropic salts (figure 1-a) in these systems shows promise for increasing the system viscosity, through elongation of spherical reverse micelles to form ellipsoidal and reversed worm-like micelles (RWLMs)4,5. This research has received external publicity through the UK government agency UK trade and Investment (UKTI)7 and is supported by an STFC funded studentship ST/L502613/1 - ?Controlling fluid properties of dense CO2? and the G8 Research Councils Initiative on Multilateral Research Funding - G8-2012 - EP/K020676/1.