Growth of M-plane GaN on (100) LiGaO 2 was achieved using plasma-assisted molecular beam epitaxy. Thermal annealing of the LiGaO 2 wafer was found to lead to a substrate surface suitable for growth. Structural and morphological analysis was performed using x-ray and reflective high energy electron diffraction, scanning electron and atomic force microscopy. X-ray diffraction results show very high phase purity and a relaxation state of the GaN film close to 80%. The surface morphology, showing characteristic M-plane streaks, is flat and smooth.