CO2 foams can be formed in water/carbon dioxide (W/CO2) mixtures with the aid of W/CO2 interfacially active hydrocarbon surfactants and surface treated silica nanoparticles (NPs). This proposal examines the nanostructure of CO2 foams; that is, CO2 pockets, aqueous films and adsorbed silica nanoparticulate (NPs) layers at the W/CO2 interface. CO2 foams have attracted much attention as they behave as viscous CO2 fluids and have the possibility to improve the efficiency of enhanced oil recovery (EOR). This SANS study will provide important information needed to advance the theory for designing W/CO2 interfacially active materials for CO2 foam formation.