A simple and highly sensitive method is proposed for the determination of Te(IV) by its catalytic effect on the reduction of thionine by sodium sulfide in the presence of cetyl trimethyl ammonium bromide as a micelle media. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of thionine at 600 nm with a fixed time of 0.5-2.5 min from initiation of the reaction. Tellurium can be measured in the concentration range of 0.6-500.0 ng/mL, with a limit of detection of 0.3 ng/mL Te(IV). The influence of more than thirty potential interfering ions was studied on the determination of tellurium. The relative standard deviation for ten replicate measurements of 0.020 and 50.0 ng/mL Te(IV) was 2.1 and 1.9%, respectively. The method was applied for the determination of tellurium in synthetic samples.