Abstract: Oscillopolarographic chelometric titrations usually use the disappearance of the incisions of the electrode active ions to be titrated to indicate end-points of titrations. When the titrated ion is not electro-active, an indicator is usually required. It was found that EDTAand its related compounds such as DTPAand CyDTAcould complex with Hg³⁺ ions produced on mercury electrode and thus yield incisions of Hg²⁺ complexes which could be used to indicate the end-point of the chelometric titra-tion. Aseries of such titrations without indicators have been developed. It was shown that direct titrations of Ca³⁺ , Mg₃₊ , Sr³⁺ , Ni³⁺ , Mn²⁺, Co³⁺ and lanthanide ions could be carried out with DTPA and CyDTA and even EDTA.