La0.5Sr0.5MnO3 thin films were deposited onto sapphire substrates by means of the pulsed-laser deposition technique. These films were characterized by several techniques including x-ray diffraction, Rutherford backscattering spectrometry, energy-dispersive x-ray, atomic-force microscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy (XPS). The cation ratios are the same in the deposited films as in the target. However, strontium segregation occurs at the film surface with an enrichment in this, element compared to Mn and La, as shown by XPS. In addition, a clear correlation between the three different contributions which compose the O(1s) XPS signal and the Sr, La, and Mn surface concentrations has been established. Annealing the films at a sufficiently high-temperature produces the same crystal structure as in the target.