We report the effect of growth temperature and annealing on microstructural, elemental and emission properties of as-grown and in-situ annealed MgZnO thin films, containing similar to 10 at. % Mg, grown at high temperature by RF sputtering. Microstructural analysis carried out by TEM reveals formation of thin oxide layer with increased layer thickness on growth temperature, in the interface between Si substrate and MgZnO thin film. Irrespective of growth temperature, increase in Mg mole fraction with increase in thickness of MgZnO thin film is observed from EDX and AES spectroscopy, and a maximum of 14 at. % Mg is observed at 800 degrees C. The photoluminescence investigation shows blue shift of 104 meV in MgZnO film grown at 800 degrees C, compared to the film grown at 600 degrees C, which is due to the enhancement of the Mg incorporation at higher temperature. In addition, annealing at the growth temperature enhanced the intensity ratio of the UV/deep level emission and increased the grain size. Thermal treatment in a vacuum improved the emission efficiency and changed the origin of the point defects. (c) 2007 Elsevier B.V. All rights reserved.