A study of macroscopic properties and microstructure of the 1 wt.% gellan gum-5 wt.% SDS-water system is presented. The complementary data obtained by DSC, NMR, rheological and CD studies allow us to conclude that the system has thermoreversible sol-I, sol-II (double helix) and gel states which are similar to those for aqueous gellan gum solutions. The micelle state of SDS molecules is not perturbed by the gellan network for the surfactant concentration up to 5 wt.%. The distinctive property of the aqueous gellan gum solutions phase diagram in the presence of SDS is the increase of the sol-helix transition temperature. A NMR diffusion and relaxation study of the SDS micelle dynamics in gellan network yields the most probable model for the sol-helix transition.