The synthesis of single crystal AlN particles has been carried out by the chemical vapor method using AlCl3 and NH3 as sources at 1450 °C. The x‐ray diffraction (XRD) measurement reveals that the samples are AlN in the wurtzite structure. The XRD line width had its minimum around partial pressure of NH3 (P (NH3)) of 0.25 atm, indicating the highest crystal quality among the samples synthesized in this study. The powders prepared at P (NH3) between 0.13 and 0.38 atm consisted mostly of particles with sizes ranging between approximately 100 and 500 nm. The particles in these samples had specific shapes with a sixfold symmetry reflecting the wurtzite crystal structure of AlN. The observation of particle morphology has also suggested that the particles composed of two crystal grains are included in the samples. The mechanism of particle formation was discussed based on the dependence of particle morphology on P (NH3). Comparison with the synthesis using vaporized Al as an Al source leads us to conclude that the use of AlCl3 is essential to the efficient formation of single crystal particles. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)