The micelle formation in aqueous sodium hexadecyl sulfate solutions is studied by small-angle neutron scattering technique. Measurements are carried out at different concentrations (1.1,2.2,3.2,5.4,10.9 and 32.8mM/dm 3) and at different temperatures (40, 50 and 60°C). The monotonous evolution of the interparticle correlation can be observed on the measured scattering patterns. At high concentrations(10.9 and 32.8 mM/dm 3) scattering patterns are described by interacting ellipsoids. At low concentrations a satisfactory fit can not be obtained by a simple form factor model. The computation of the distance distribution function proved the ellipsoial shape at 10.9 and 32.8 mM/dm 3, but showed an unexpectedly large particle dimension and structurization of the particle at lower concentrations. An assumption is made on the phase transition in the concentration range studied.