Four azo compounds based on diazotization of 2-aminobenzothiazole have been synthesized and characterized by elemental analysis as well as different spectroscopic techniques. The potentiality of the prepared compounds as new chromogenic reagents for the spectrophotometric determination of Mo was studied by extensive investigation of optimum conditions favouring the formation of the coloured complexes. Beers law is obeyed in the concentration range 0.2-8.5 μg ml whereas Ringbom optimum concentration range was 0.8-7.5 μg ml. The detection limit was 0.05 μg ml. The molar absorptivity and Sandell sensitivity of the formed complexes are calculated. The effect of interfering ions on the determination of Mo was investigated. The relative standard deviations for six replicate determinations of 5.0 μg ml of Mo are 1.23, 1.47, 1.05 and 1.38 % using reagents I, II, III and IV, respectively. The proposed method has been applied to investigate the amount of Mo in human urine samples. The molybdenum levels found between 0.5-2.1 μg/100 ml.