Se crecieron peliculas delgadas de MoO 3 dopadas con Cerio empleando la tecnica de atomizacion pirolitica utilizando una solucion de (NH 4 ) 6 Mo 7 O 24 .4H 2 O 0.1 M. El dopado se realizo adicionando CeCl 3 .7H 2 O 0.1M, en una relacion de 2% en volumen. Los espectros de rayos X y de electrones Auger muestran la incorporacion de Ce en la pelicula de MoO 3 . Los espectros de difraccion de rayos X indican que la insercion del Cerio destruye la estructura a-MoO 3 observada en las peliculas sin dopar. Las propiedades electroquimicas se estudiaron con la tecnica de voltametria ciclica entre -400 y 400 mV a velocidades de barrido desde 16 hasta 144 mV/s. Se establecio que el coeficiente de difusion varia desde 1.06 x 10 -10 cm 2 /s, para la pelicula sin dopar, hasta 3.49 x 10 -10 cm 2 /s para la pelicula dopada. Las medidas de transmitancia optica en el rango 290-2500 nm mostraron que la transmision de la luz de la pelicula dopada con Cerio es superior en un 10% con respecto a la pelicula sin dopar. Cerium-doped MoO 3 thin films were grown through spray pyrolysis using (NH 4 ) 6 Mo 7 O 24 .4H 2 O 0.1 M solution. The doping was performed by adding 0.1M CeCl 3 .7H 2 O, 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 a-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.