The reagent N,N-diethyl-N'-benzoylthiourea produces a green complex with rhenium in hydrochloric acid medium in the presence of tin(II) chloride. The complex extracted into toluene shows an absorption maximum at 383 nm, obeys Beer's law from 1.5 to 22 mug ml(-1) of rhenium while its molar absorptivity and Sandell sensitivity are 6.66 x 10(3) L mol(-1) cm(-1) and 0.028 mug cm(-2), respectively. It tolerates the presence of a large number of ions, including Mo(VI), W (VI) and some platinum metals. Job's and the mote ratio methods indicate that the rhenium metal and the chelating agent ratio of 1:2 in solution. The system has been applied to the determination of rhenium on synthetic samples and alumina based catalysts.