Seven chelating agents were used for complexation of Cu, Fe, Mn and Zn microelement ions in N, N-P and N-P-K fertilizing media at pH 3-7 and varying chelating agent-to-microelement molar ratio. The complexation degree was detd. by differential pulse voltammetry. It increased with increasing pH of the medium. The highest complexation degrees (mostly 80-100% except for Cu) were obsd. for EDTA, diethylenetriaminopentaacetic acid and 2-hydroxyethylenediaminotetraacetic acid.