The epitaxial growth of the artificial hexagonal GdMnO3 phase was investigated on substrates with hexagonal symmetries. The GdMnO3 thin films grown on Pt(1 1 1)/Al2O3(0 0 0 1) substrates showed a mixed state of a dominant hexagonal phase and small additional orthorhombic phases, which were stable in bulk. In this study, high oxygen partial pressures during film deposition were found to help to fabricate GdMnO3 thin films in the dominant hexagonal phase. Also, the growth behavior of the small additional orthorhombic GdMnO3 phases was studied by X-ray diffraction (XRD) measurements with a synchrotron radiation X-ray source. This study confirmed that even the orthorhombic GdMnO3 phases prefer specific orientations on the substrates with an in-plane hexagonal symmetry. (C) 2007 Elsevier B.V. All rights reserved.