Electrochemical properties of ruthenium oxide films with different degrees of crystallinity were studied. The films were grown by pulsed laser deposition at substrate temperatures from 30 to 400°C. At low temperatures, the amorphous phase of films was formed. At high temperatures, the crystalline phase of films was obtained. From the cyclic voltammetric study in solution, it was found that the current response for an electrode of the amorphous film was higher than that of the crystalline film. A proton diffusion length of larger than 5.8 nm was obtained on the film prepared at 30°C.