Nanocrystalline aluminum nitride (AlN) with surface area more than 30 m(2)/g was synthesized by nitridation of nanosized delta-Al2O3 particles using NH3 as a reacting gas. The resulting powders were characterized by CHN elemental analysis, X-ray diffraction (XRD), Fourier transform infrared spectra, X-ray photoelectron spectra, field-emission scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller surface area techniques. It was found that nanocrystalline delta-Al2O3 was converted into AlN completely (by XRD) at 1350 degrees-1400 degrees C within 5.0 h in a single-step synthesis process. The complete nitridation of nanosized alumina at relatively lower temperatures was attributed to the lack of coarsening of the initial delta-Al2O3 powder. The effect of precursor powder types on the conversion was also investigated, and it was found that alpha-Al2O3 was hard to convert to AlN under the same conditions.