Small lattice-mismatched beta-LiGaO2 (001) substrates have been used for the epitaxial growth of (0001) Zn1-xMgxO films using the metallorganic chemical vapor deposition method. Structure characterizations by employing X-ray diffraction and transmission electron microscope demonstrate that no MgO or Mg cluster exists throughout the Zn1-xMgxO films. The epitaxial (0001) Zn1-xMgxO films are successfully grown on the (001) LiGaO2 substrates with the epitaxial relationship of [0002](ZnMgO)parallel to[002](LGO) and [10 (1) over bar0](ZnMgO)parallel to[200](LGO). Polarity of the Zn1-xMgxO films is determined by the convergent beam electron diffraction technique as well as wet chemical etching. Both results indicate the Zn-polarity of Zn1-xMgxO films. The room-temperature cathodoluminescence spectra of the epitaxial (0001) Zn1-xMgxO films show an obvious blueshift of the near-bandedge emission with increasing Mg content, suggesting a successful bandgap engineering in the epitaxial (0001) Zn1-xMgxO films on the (001) LiGaO2 substrates. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3514622] All rights reserved.