Galvanostatic electrodeposition was used to produce transparent and amorphous WO3 films that showed color changes from clear to blue in response to the applied potential of +/- 1.0V. The 61% in transmittance variation was measured at wavelength of 633nm. The roughness of 16.7nm was obtained by atomic force microscopy (AFM). The scanning electron microscopy (SEM) evidenced homogeneous morphology without cracks but with some regularly disposed spots attributed to the nucleation sites. The SEM images also confirmed the thicknesses of 143nm. The electro-optic data analysis gave the coloration efficiency value of 11.6cm(2)/C. Finally, the electrical measurements evidenced an existence of the negative capacitance.