Wurtzite InN films of c-axis orientation have been grown on as-received and water-immersed (111)SrTiO3 (STO) substrates by metal-organic chemical vapor deposition. The epitaxial relationships between InN films and STO substrates are investigated by X-ray diffraction. Two kinds of in-plane alignment of [11 (2) over bar0](InN)parallel to[1 (1) over bar0](STO) and [1 (1) over bar 00](InN)parallel to[1 (1) over bar0](STO) with a 30 degrees rotation relative to each other have been realized on as-received and water-immersed (111)STO substrates, respectively. The in-plane orientation of InN relative to STO is strongly dependent on substrate pretreatment, but not sensitive to growth temperature and trimethylindium flow rates. The difference in terminated surfaces of as-received and water-immersed STO substrates are postulated to be responsible for the change in epitaxial relationships. Compared with each other, the in-plane epitaxial relationships of [1 (1) over bar 00](InN)parallel to[1 (1) over bar0] STO and [11 (2) over bar0](InN)parallel to[1 (1) over bar0](STO) are respectively energetically preferred due to a higher bonded density and thus a lower interface energy on SrO3- and Ti-terminated STO substrates. (C) 2011 Elsevier B. V. All rights reserved.