The electrochemical behavior of TiCl3 and TiCl4 was studied in ALCl(3)/DMSO2 electrolyte at 130 degrees C. The main Ti-III and Ti-IV species formed in the AlCl3/DMSO2-based electrolyte might be TiCl(3-n)(n+) and TiCl(4-m)(m+), respectively. The reduction of Ti-IV to Ti-II is a multistep process (one electron transferred in each step). The diffusion coefficient values of Ti-III and Ti-IV species have been calculated from voltamperometric and chronoamperometric investigations. Analysis of sampled current voltammograms indicates that the Ti-IV/Ti-III process is a quasi-reversible redox system with E-1/2 close to 3.575 V vs Li+/Li and that the reduction of Ti-III to Ti-II might involve an electrochemical-chemical mechanism, i.e., electron transfer followed by a destructive reaction or a disproportionation of Ti-II species. In the 2 to 4 V potential range, metallic titanium deposition is not observed.