DC and AC polarographic behavior of titanium(IV)-trans-cyclohexane-1, 2-diamine-N, N, N', N' -tetraacdtate (CyDTA) and N-(2-Hydroxyethyl)ethylenediamine-N, N, N' -triacetate (EDTA· OH) chelates was studied in detail. In acidic EDTA· OH solution and CyDTA solution, titanium(VI) chelate ion gave invariably a single well-defined, reversible polarographic wave, corresponding to the following one-electron reduction.Ti(OH)nXn- + e + nH+ ↔ TiX- + nH2OTi(OH)nX1-n + e + nH+ ↔ TiX2- + nH2O (n=0, 1, 2, .....)where X is CyDTA and Y shows EDTA· OH.In the cace of CyDTA-titanium(IV) chelate, one hydrogen ion is involved at 1.3< pH< 3. O and two hydrogen ion involved at 3.0< pH< 5.5 in the ele ctrode reactioni In the case of EDTA· OH-titanium(IV)ehelate, one hydrogen ion is related to the electrode reagtion below pH 4. As the pH increased, polaregraphic wave became more irreversible, diffusion current decreased and the selution became colloidal in both cases.From the relation between the half-wave potential and the concentration of hydrogen ion, chelating agent and electrolyte, the compositions and the dissociation constants of titanium(IV)- CyDTA, titanium(IV)-EDTA· OH chelates, and titanium(III)-CyDTA, titanium(III)-EDTA· OH chelates in solution were determined.