The first reduction step of di(propylthiotetramethylcyclopentadienyl) titanium dichloride (Cp2TiCl2) in THF solution has been investigated by cyclic voltammetry under steady-state conditions, cyclic voltammetry in diffusion and in thin layer. The results can be interpreted in terms of a square scheme with ligand-exchange chemical reactions. The thermodynamic and kinetic parameters have been obtained by simulation. The rate constants of the charge transfer, derived from the voltammetric curves, are rather slow (k(hi) = 0.025 cm s(-1)). The equilibrium Cp-2'TiCl2 + L/Cp-2'TiClL+ +Cl- is determined by the fast recombination of the chloride ion and the cation (K-1 = 2.4 x 10(-11) M, k(b1) congruent to 10(11) M-1 s(-1)); whereas the equilibrium Cp-2'TiCl2- + L/Cp-2'TiClL + Cl- is in favour of the chloride ion departure (K-2 = 0.01 M) with a fast reaction rate (k(f2) = 1000 s(-1)). (C) 2003 Elsevier Science B.V. All rights reserved.