Recently the research of new types of surfactants has lead to the synthesis of the so called gemini surfactants, both anionic and cationic, showing very interesting properties. They are constituted by two not terminal hydrophilic groups and two hydrophobic groups per molecule, separated by a spacer. The application of these molecules in industrial processes could lead to a dramatic reduction in the concentration of surface active material for the same performance. Because of the great interest of gemini surfactants, both from an applicative and a speculative point of view, the literature about the synthesis, the chemico-physical and biological properties of this class of compounds is briefly reviewed. Particular attention is devoted to the thermodynamic properties of the homologous series of amphiphilic N,N`-bisdimethyl-1,2-ethanediammine derivatives, of general formula/C_nH_2n+1OOCCH₂(CH₃)₂N⁺CH₂CH₂N⁺(CH₃)₂CH₂-COOC_nH_2n+/2CI^- (bis-C_n-BEC, where the subscript n  stands for the number of carbon atoms of the alkyl chain bound to the carboxyl group).