Energy dispersive X-ray diffraction (EDXD) measurements were conducted on fully hydrated samples of the cationic gemini surfactant (2S,3S)-2,3-dimethoxy-1,4-bis(N-hexadecyl-N,N-dimethylammonium)butane dibromide, SS, as a function of temperature. The surfactant molecules self-assemble into multilamellar vesicles with a well-defined d-spacing which decreases as temperature increases. The derived structural parameters, such as bilayer thickness, size of the water region interbilayer, number of water molecules per surfactant molecule reveal reduced bilayer fluctuations, as a function of increasing temperature, consistent with the observed reduction of the water layer. (C) 2004 Elsevier B.V. All rights reserved.