La0.6Ca0.4CoIr0.25O3.5-delta was prepared by a mechanical alloying process from mixtures of La0.6Ca0.4CoO3 and IrO2. Scanning electron microscopy images on the resulting powders exhibited particles with irregular shape at 300-500 nm in size. X-ray diffraction analysis confirmed formation of a perovskite with complete disappearance of rutile signals from IrO2, indicating successful incorporation of Ir4+ at the Co3+ sites. Supported on carbon nanocapsules, the La0.6Ca0.4CoIr0.25O3.5-delta demonstrated superior performance over those of La0.6Ca0.4CoO3 in both charging and discharging current density-voltage polarizations. In addition, galvanostatic charging and discharging measurements at 25 and 100 mA/cm(2) indicated that the electrocatalytic abilities of La0.6Ca0.4CoIr0.25O3.5-delta are stable and sustainable.