This paper presents a systematic investigation of AlN nanowire synthesis by chemical vapor deposition using Al and NH 3 on SiO 2/Si substrate and direct nitridation of mixture of Al-Al 2O 3 by NH 3. A wide variety of catalyst materials, in both discrete nanoparticle and thin film forms, have been used (Co, Au, Ni, and Fe). The growth runs have been carried out at temperatures between 800 and 1100°C mainly under H 2 as carrier gas. It was found that the most efficient catalyst in terms of nanowire formation yield was 20-nm Ni film. The AlN nanowire diameters are about 20-30 nm, about the same thickness as the Ni-film. Further studies of direct nitridation of mixture of Al-Al 2O 3 by NH 3 have resulted in high density one-dimensional nanostructure networks at 1100°C. It was observed that catalyst-free nanostructures resulted from the direct nitridation were significantly longer than that with catalysts. The analysis of the grown nanowires has been carried out by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and x-ray diffraction. © 2011 Materials Research Society.