LiNi0.5Mn1.5O4 thin films were prepared by pulsed laser deposition (PLD) on stainless steel substrates. The growth of the films has been studied as a function of substrate temperature and oxygen partial pressure in deposition, using X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM). Electrochemical properties of LiNi0.5Mn1.5O4 thin film cathodes were investigated using cyclic voltammetry and galvanostatic charge/discharge against a lithium anode. The initial capacity and capacity retention of the films are highly dependent on the crystallinity and purity of the films. LiNi0.5Mn1.5O4 thin films grown at 600°C in an oxygen partial pressure of 200mTorr are well crystallized with high purity, exhibiting excellent capacity retention between 3 and 5V with a LiPF6-based electrolyte.