Thin films of amorphous alumina of thickness 350 nm were deposited on fused silica substrates by electron beam evaporation. Amorphous films were annealed at several temperatures in the range: 400-1130 degrees C and changes in film crystallinity, short-range structure, optical and mechanical properties were studied. X-ray diffraction studies found that crystallization starts at 800 degrees C and produces gamma and delta-alumina, the latter phase grows with heat treatment and the sample was mostly delta and theta-alumina after annealing at 1130 degrees C. The as-deposited amorphous alumina films have low hardness of 5 to 8 GPa, which increases to 11 to 12 GPa in crystalline sample. Al-27 Magic Angle Spinning Nuclear Magnetic Resonance was used to study the short-range order of amorphous and crystalline alumina films and it was found that amorphous alumina film contains AlO5 and AlO4 structural units in the ratio of 1:2. The concentration of AlO5 was significantly suppressed in crystalline film, which contains 48% of Al3+ ions in AlO6, 7% in AlO5 and 45% in AlO4 units. (C) 2014 Elsevier B. V. All rights reserved.