The energy transfer between Rhodamine 6G and Rhodamine B dyes in aqueous solution of Na dodecyl sulfate (I) was studied. The energy transfer between both dyes was observed when the concentration of I was far below the crit. concentration of normal micelle formation, indicating the premicelle was formed at this concentration The IA/(IA + ID) (IA and ID are the fluoroscence intensity of the acceptor and donor, resp.) from the fluorescence spectrum was used as an indication of energy transfer efficiency and a max. value of this efficiency existed on the increase of I concentration The max. value of efficiency was shifted to the higher concentration of I when different amts. of DMSO were introduced to the solvent-water system. This demonstrated that the hydrophobic interaction was the driving force for the premicellar formation of I mols.

Key words: MICELLE, DYES, SODIUM SULFATE, C12 COMPOUNDS, RHODAMINE B, ENERGY CONVERSION, RHODAMINE-6G