Cerium-doped MoO 3 thin films were grown through spray pyrolysis using (NH 4)6Mo 7O24 .4H 2O 0.1 M solution. The doping was performed by adding 0.1M CeCl 3.7H 2O, in a ratio of 2% by volume. X-ray and Auger electron spectra show of Ce incorporation in MoO 3 thin film. X-ray diffraction showed that Cerium insertion destroys the α-MoO 3 structure observed in undoped films. The electrochemical properties were studied using the cyclic voltammetry technique with -400 to 400 mV and scanning speeds from 16 to 144 mV/s. It was established that the diffusion coefficient varies from 1.06 x 10 -10 cm 2 /s for the undoped film to 3.49 x 10 -10 cm 2 /s for doped film. This suggests that the doped film favors ion exchange processes. The optical transmittance in the range of 290-2500 nm showed that the light transmission of the film doped with Cerium is higher by 10% compared to the undoped film.