The kinetics of the reduction of perchlorate ion by Ti+3 in dilute solutions has been studied. The rate of reaction has been determined at various concentrations H+, ClO4- , and Cl-. The pseudo first order rate constants were calculated from plots of ln[TTi+3] vs. time and the nature of the H+, ClO4-, and Cl- dependences was also determined;The reaction appears to proceed by more than one path. There is a reaction which is independent of both H+ and Cl-. The reaction was also found to be first order in H+ and to be retarded considerably by addition of chloride. No Ti+3-ClO 4- complexes ware found to exist even at high concentrations of ClO4-;The rate of disappearance of total titanium was found to follow the rate expression, -dTTi+3 dt= k1+k2K1 Cl+k3H+ +k4K1 Cl- H+1+K1 Cl- ClO4 TTi+3. The rate constants were determined at two temperatures and the activation energies and entropies were calculated. The most favorable mechanisms appear to be those which involve perchlorate ion reacting with hydrated Ti+3 and the complex TiCl++;The following kinetic mechanisms have been proposed: Ti+3+ClO4 -&rlhar2;complex →ClO3+TiO++, Ti+3+ClO4-+ H+&rlhar2;complex →ClO3+TiOH +3, TiCl+2+ClO4- &rlhar2;complex→ ClO3-TiO+++Cl- orTiOCl +, TiCl+2+ClO4-+H+ &rlhar2;complex→ ClO3+TiOH+ 3+Cl- orTiOHC l+. In each case the rate determining step is the disproportionation of the coordinated complex. The radical ClO3 reacts further in a series of rapid one electron transfer reactions to the final product, Cl -.