Abstract Europium fluorescence sensitized by tetracycline, via the formation of an organic chelate, was used for the sensitive detection of tetracycline. The efficiency of the intramolecular energy transfer and of the resulting ion luminescence was studied by fluorescence and thermal lens spectrometry. The sensitivity of the method depends on the pH and the concentration of the emitting ion and it is increased by the addition of Triton X-100 to the aqueous solution. The fluorescence enhancement obtained in the micellar medium is correlated with an increase in the fluorescence lifetime of europium emission. Detection limits for tetracycline are 1.0 X 10 −8 and 3 X 10 −9 M in the absence and presence of Triton X-100, respectively.