TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The Pd-based catalyst is a Pd catalyst or an alloy catalyst comprising at least one metal comprising iridium (Ir), cobalt (Co), nickel (Ni), titanium (Ti), vanadium (V), chromium (Cr), zinc (Zn), manganese (Mn), copper (Cu), iron (Fe), niobium (Nb), indium (In), tin (Sn), tungsten (W), or cerium (Ce), and Pd. The amount of the Pd-based catalyst is 1-70 parts by wt% based on 100 parts by wt% of the total sum of weights of the complex support and the Pd-based catalyst. The Pd-based catalyst has an average diameter of 2-15 nm. The metal oxide comprises at least one comprising Ti, boron, Sn, In, V, W, molybdenum (Mo), Mn, Ce, Nb, Cr, zirconium (Zr), Zn, Fe, or tellurium (Te). The metal oxide has crystallinity. The carbon-based material is one comprising Ketjenblack (RTM: Electroconductive carbon black), carbon black, graphite carbon, carbon nanotube, or carbon fiber. The amount of the metal oxide is 0.01-70 wt% based on 100 wt% of the complex support. The precursor of the Pd-based catalyst comprises at least one comprising palladium nitride, palladium chloride, palladium sulfide, palladium acetate, palladium acetylacetonate, palladium cyanate, palladium isopropyl oxide, or palladium butoxide. Preferred Method: The Pd-based catalyst is disposed on the carbon-based material or the metal oxide. The Pd-based catalyst is combined with the metal oxide. In the method, forming of the complex support comprises: dissolving a metal precursor for forming the metal oxide in a solvent and preparing a mixture solution for a complex support; adding a carbon-based material to the mixture solution for a complex support and stirring; drying the mixture solution for a complex support, to which the carbon-based material is added, to disperse the metal precursor on the carbon-based material; and oxidizing the metal precursor dispersed on the carbon-based material and forming a metal oxide dispersed on the carbon-based material. In the method, forming of the complex support further comprises thermally treating the carbon-based material, on which the metal oxide is dispersed, under an inert gas atmosphere, to improve crystallinity of the metal oxide.    TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The electrode is a cathode, and an anode. EXAMPLE - Isopropyl titanium oxide (Ti(OCH(CH3)2)4) as a titanium (Ti) precursor (0.78 g) was impregnated with Ketjenblack (RTM: Electroconductive carbon black) (1 g), using incipient wetness impregnation and was calcined at 300 degrees C in the air, to oxidize the Ti precursor into a Ti oxide. Then, Ti oxide/carbon (TiOx/C) complex support (0.3 g) was added to a mixture solution (40 g) obtained by dissolving a palladium nitride (0.76 g), as a palladium (Pd) precursor, in distilled water and was stirred. The mixture solution was dried at 50 degrees C by distillation under reduced pressure. Then, a dried resultant was thermally treated at 200 degrees C under a hydrogen atmosphere so that the Pd precursor was reduced to Pd, to obtain a Pd/TiOx/C electrode catalyst.    x = not defined.