The synthesis of a mixed lithium titanium spinel Li4/3Ti5/3O4 obtained via a sol-gel process in non aqueous media is reported. The electrochemical behaviour of the sol-gel Li4/3Ti5/3O4 spinel oxide is examined. A voltage plateau located at 1.55 V corresponds to the reversible insertion of 0.95 lithium ions in this compound while the structure is shown to be unchanged. The chemical diffusion coefficient of lithium has been evaluated by a.c. impedance: D-Li is found equal to 3 X 10(-12) cm(2) s(-1) for x = 0.2 in Li(4/3+0.2)Ti5/3O4.