Sensitized biacetyl Room Temperature Phosphorescence by α -Naphthylacetic acid in reversed micelles of AOT-C6H12-H2O is presented. The intensity of biacetyl RTP is enhanced about 13 times than the intensity observed in aqueous SDS micelles. Parameters including the concentrations of AOT, solubilized water as well as donor and accepter concentration that may influence the sensitized biacetyl phosphorescence are also examined. The absorption spectra and characteristics of luminescence as well as microviscosity data are used to elucidate the factors that affect sensitized phosphorescence. The intensity of sensitized biacetyl phosphorescence in AOT reversed micelles is determined by the lifetime of sensitized biacetyl, energy transfer efficiency and the Poisson distribution. No remarkable influence of water content on the intensity of sensitized biacetyl phosphorescence is observed at W([H2O]/[AOT]) less than 20 because the effects of both decreasing in microviscosity and increasing in radius of inner core of reversed micelles offset each other. The decreasing in sensitized biacetyl RTP is observed at W more than 20. The detection limits for α -naphthylacetic acid and biacetyl are 2.0×10^-^8mol.dm^-^3 and 8.5× 10^-^9mol.dm^-^3, respectively.

Key words: ULTRAVIOLET SPECTROPHOTOMETRY, MICELLE, FLUOROSPECTROPHOTOMETRY, PHOSPHORESCENCE, NAPHTHALENEACETIC ACID, DIACETYL, SENSIBILIZATION AGENT