Three-phase gas-diffusion oxygen electrodes for metal air battery were prepared and characterized. Nano-structured γ-MnO2 catalysts were synthesized by solid state redox reaction of two compounds, Mn(CH3COO)2·4H2O and C2H2O4·2H2O. Their crystal phase, morphologies and particle size were characterized by XRD, TEM, respectively. The electrochemical property of three-phase gas-diffusion oxygen electrodes composed of nano-structured γ-MnO2 catalysts for oxygen reduction was examined by using the linear polarization method in a neutral solution. Besides, the surface morphologies of the catalytic layer of three-phase gas-diffusion oxygen electrodes were also investigated by SEM. Experimental results revealed that these kinds of three-phase gas-diffusion oxygen electrodes have excellent electrochemical performance. The optimal proportion of nano-structured γ-MnO2 catalysts in the catalytic layer was 60wt.%. Three-phase gas-diffusion oxygen electrodes composed with nano-structured γ-MnO2 catalysts appear to be a highly possible candidate for applications in neutral solution metal air battery.