 Nitridated LiMn1.5Ni0.5O4 was prepared by a solid-state reaction followed by nitridation to investigate the effect of nitrogen on the structural and electrochemical performance of LiMn1.5Ni0.5O4 cathode material for lithium-ion batteries. The structural and morphological features of the synthesized samples were characterized by various techniques. X-ray photoelectron spectrometer analysis revealed the existence of a trace amount of nitrogen on the surface and slight changes in Mn and Ni valence states. Electrochemical studies on the nitridated LiMn1.5Ni0.5O4 was conducted using the galvanostatic charge–discharge process and electrochemical impedance spectroscopy. The nitridated LiMn1.5Ni0.5O4 exhibited enhanced cyclability and rate capability compared with LiMn1.5Ni0.5O4, which originated from the improved electrical conductivity caused by increased proximity between active Ni redox centers as well as the increased number of Mn3+ hopping carriers.