By spectrophotometric method, compex formation of molybdenum (VI) with 2,3,4- trioxy-4’—sulfoazobenzene in the presence of non-ionic surface-active substances-triton X-114 has been studied. It has been established, that the polyligand complex with proportion 1:1:1, is formed in 0.1 M HCl medium and light absorbtion in λ=490 nm. Compliance with Beer’s law is carried out in an interval of molybdenium (IV) concentration of 0.19-1.536 mkg/25 ml, molar of absorbtion of the complex is 4.8 . 104. High selective photometric method for determination of molybdenum (VI) in technological waters has been worked out