We report direct observations of the nucleation and early stages of growth of GaN nanowires. The nanowires were formed by exposing Au + Ga droplets to ammonia. The formation process was observed in situ, and controlled in real time using an environmental transmission electron microscope. Observations show that nuclei forms only at thin region of the Au + Ga, following only the VLS mechanism. The droplet-nanowire interface in the initial stages is multi-faceted, and become planar during the growth. Chemical and structural analysis shows that the resulting nuclei are GaN with the wurtzite structure. (C) 2011 Elsevier B.V. All rights reserved.