The epitaxial strain can modify the physical properties of complex oxide thin films considerably. The strain effect is expected to be less pronounced for relatively thick films and the physical properties should resemble to the bulk material. However, it has been recently observed that the electronic and magnetic properties of La0.5Ca0.5MnO3 thin films deposited on (111) SrTiO3 substrates thicker than a threshold value differ considerably from the bulk material. This observation is a hint for some interesting microstructural features in these films. In the present study, the microstructure of La0.5Ca0.5MnO3 thin films on (111) SrTiO3 substrates is investigated by X-ray diffraction and high resolution transmission electron microscopy. (C) 2009 Elsevier B.V. All rights reserved.