The polarographic study of the behaviour of antimony (Ⅲ) complex with 1,2-diamino-cyclohexane-tetraacetic acid (H₄Z),including the calculation of its stability constant and thermodynamic functions and the mechanism of complex formation, has not yet becn made in detail. If to an acidic 4 M sodium chloride solution, a certain amount of 1,2-diamino-cyclohexane-tetraacetic acid is added, two waves corresponding to three electrons electrode reaction of antimony(Ⅲ) appear. An increase in pH of the supporting electrolyte or in concentration of 1,2-diaminocyclohexane-tetraacetic acid results in an increase of the second wave (at more negative potential) at the expense of the original one. The limiting current of the total wave remains constant and is independent of the concentration of 1,2-diaminocyclohexane-tetraacetic acid and the pH values.The first wave is reversible and kinetically controlled by the rate of chemical reartion, whereas the sum of both waves is diffusion controlled. This is proved by the dependence of the wave height on the height of the mercury reservoir, by the time beater(Fig. 1),by the temperature dependence, by the hanging mercury drop electrode and by the oscillographic polarograph (Fig. 2).