Electrochemical properties and morphologies of platinum thin films on the conductive ceramics TiO and Ebonex (Ti4O7) have been examined. While Ebonex is known to be good material for an electrode substrate, the electrodeposition of Pt at the Ebonex surfaces requires high overpotentials, which results in the growth of Pt grains with large holes probably caused by H-2 evolution at the electrode surfaces from the electrolyte solution. After scanning a few decades of potential cycles between far positive and negative ranges continuously, the platinum films become more densely packed and spread evenly. TiO shows better characteristics as a substrate for electodeposition of platinum. The electrochemical properties of the Pt-deposited TiO is the same as those of the Pt electrode.