Preparation and analysis of sodium decylsulphonate (SDSNATE), as well as the elaboration of the ternary and quaternary phases diagram are here presented. The lyomesosphases were studied by: polarizing microscopy, small angle X-ray scattering, densimetry and refratometry. We compare the present results on the SDSNATEsystems to sodium decylsulphate systems and perhaps the most important point is that the SDSNATEis free of hydrolysis for all mesomorphic purposes, i.e. the SDSNATEis thermally stable.