Abstract: The mixed catalytic rate(ν_mix)of the reaction between I₃^- and Ti³⁺ions on reduced Pt surface has been calculated through the electrochemical study on electrode reactions of I₃^-/I^-and Ti³⁺/Ti⁴⁺. When the mixed potential(E_mix)lies in the limiting current region, ν_mix is independent of Ti³⁺concentration and is first order to. ν_mix is also proportional to the square root of the rotating speed of electrode. There is only small differences in ν_mix as the H⁺ concentration changes. Results obtained by electrochemistry agree with the results measured by kinetic method. The results of this heterogeneous catalysis in solution have been predicted and explained by pure electrochemistry.

Key words: triiodide ion, titanium(Ⅲ)ion, rotation disk(Pt)electrode, electrochemistry, kinetics