Liquid-state ion-storage layers which are commonly used for electrochromic devices (ECDs) have the problem of liquid leakage caused from mechanical damage or time degradation of sealing materials. To overcome this drawback, we tried to form Sn(O, H)(x) films comprising mixtures of tin oxide (SnO2) and tin hydroxide (Sn(OH)(4)) by electrodeposition in order to apply them to the solid-state ion-storage layers of solid-state ECDs. The Sn(O, H)(x) films were formed by anodic potentiostatic electrodeposition at 0.2 V vs. Ag/AgCl using 0.01 mol/L SnSO4 aqueous solution. Characterization of the samples with X-ray diffraction, energy dispersive X-ray spectrometry, Fourier transform infrared spectroscopy revealed that they are composed of SnO2 and Sn(OH)(4). Moreover, a coloring experiment of an ECD having a structure of FTO/WO3(H2O)(0.33)/Sn(O, H )(x)/Cu was carried out under the application of a voltage, and it changed the color from pale yellow to blue in the coloring experiment. This result shows that the Sn(O, H)(x) films possesses the function as the solid-state ion-storage layers of solid-state ECDs.