The aggregation behavior of the cationic fluorocarbon surfactants 1,1,2,2-tetrahydroperfluoroalkylpyridinium chloride and 2-hydroxy-1,1,2,3,3-pentahydroperfluoroalkyldiethylammonium chloride in aqueous solution have been studied using cryo-transmission electron microscopy as the main technique. The effects on aggregate structure of factors such as surfactant and salt concentration, counterion type, and alkyl chain length were investigated. Similar to hydrocarbon surfactants the fluorocarbon surfactants Self-assemble into various aggregates such as micelles, threadlike micelles, vesicles, and other lamellar aggregates. A distinctive property of the fluorocarbon surfactants is their tendency to form structures with little curvature, such as cylindrical micelles and bilayer structures. Even a very small reduction of the repulsion between the headgroups is sufficient to accomplish a sphere to rod transition, so that a solution of globular micelles in water is turned into a highly viscous, sometimes viscoelastic solution on the addition of low concentrations of a simple salt. The differences between the fluorocarbon and hydrocarbon surfactants are discussed.