The Raman spectrum of a surfactant is dominated by the vibrational modes of the hydrocarbon chain. The C-H stretching region &lpar;2800–3000thinsp; cm−1) is very sensitive to the lateral order of the molecule and the microenvironment of surfactant systems. The study of the phase diagram of the dodccyl bctaine, 1-butanol, water system and the microstructurc of surfactant solutions studied by their Raman spectra has helped us to discover an important new parameter. We regard this parameter (R’ = I2910/ I2910l288a) as a phase verification for surfactant systems, in which R1> 1 indicates the presence of lamellar liquid crystal and R’ < 1 indicates a micellar solution.