Ionic liquids (ILs), which are defined as salts with a melting point below 100 C are often considered as future solvents for catalysis, chemical reactions, extractions and electrochemical purposes. Apart from these classical applications, they have also gained interest in classical colloid and surface chemistry. The formation of amphiphilic association structures in and with ionic liquids, such as micelles, vesicles, microemulsions and liquid crystalline phases have been reported in literature. All studies concerning ILs in microemulsions described in literature have been performed below the boiling point of water. In the present work, we were interested in microemulsions that are stable over a wide temperature range at ambient pressure. For this purpose, water must be replaced by a room temperture ionic liquid (RTIL).The thesis can be subdivided into three main parts: Conductivity studies of the anion effect on imidazolium based ionic liquids over a wide temperature range (-25-195) C, formulation and characterization of nonaqueous, high temperature stable microemulsions with RTILs as polar phase and the synthesis and characterization of new ionic liquids based on alkali cations."