It has been synthesized 1-(2-tenoil)-4-threefluor-2 [-2-hydroxy-5- sulfonaphthalineazo] bythadione-1,3 (R) on the basis of 2-tenoilthreefluorasetone . It has been studied a stability of complexes of some metals with this reagent by the potentiometric and conductometric titrations methods. The basic spectrofotometric characteristics of reaction of copper with the synthesized reagent have been established. Influence foreign ions and masking substances on complex formation have been researched. The technique of photometric definition of copper (II) in alloys on basis of zinc has been developed.