Crystalline aluminum nitride thin films (∼ 1200 Å) were prepared via nitridation of amorphous aluminum oxide and characterized by XRD, SEM, TEM, oxygen resonance, Auger depth-profile analysis and ellipsometry. Precursor chemistry, heating rate, nitridation temperature and nitridation time were varied to explore the competition between densification, crystallization and nitridation. Oxygen content in the films decreased with increasing nitriding temperature or nitriding time. Heating rate was determined to have minimal effect on the oxygen content for the parameters evaluated. A modified Kissinger analysis of DTA data for the crystallization of α-Al2O3 yielded an effective activation energy of ∼104 kcal/mol.