The spectral properties of a cyanine dye were studied in different systems, especially in the reversed micelles, a system for water in oil. Due to the space limitation and electrostatic effect of the water cell in reversed micelles, the optical behavior of the dye in reversed micelles was very different from in water and alcohol. The effect of alcohol content, omega (omega = [water]/[surfactant]) and temperature on absorption and fluorescence spectra in these systems were studied. In reversed micelle the dye showed characteristics of two monomolecular states, the balance between which could be affected by all factors investigated above.