The development of catalysts with high catalytic activity is needed to improve the sluggish reaction kinetics in Li-O-2 batteries. In this study, nano-sized alloy particles derived from metal precursors were employed as a bimetallic catalyst in a Li-O-2 cell, with their high activity and uniform distribution serving to enhance energy efficiency, cycle life, and capacity retention. A cell fabricated with a palladium-cobalt/multi-walled carbon nanotubes (Pd3Co/MWCNTs) electrode was able to stably reach 70 cycles, whereas cells with MnO2/KB and KB electrodes lasted only 17 and 10 cycles, respectively. During the first charging cycle, the cell with a Pd3Co catalyst exhibited a 200 mV lower overpotential than the cell with a MnO2/KB electrode, and a 490 mV lower overpotential than when a KB electrode was used. The Pd3Co/MWCNTs cell also demonstrated superior capacity retention of similar to 94.5% (5th cycle) and similar to 88.7% (20th cycle), with impedance analysis revealing an enhanced reversibility that confirms the improvement in cycle performance. (C) 2015 The Electrochemical Society.