Titanium coatings were deposited on glass substrates by electron beam evaporation in both argon and neon at pressures from 0.33 to 2.00 Pa and also under vacuum (4 X 10(-4) Pa) conditions. X-ray diffraction was used to assess the effect of gas pressure on coating preferred orientation, microstrain, and crystallite size. The addition of either argon or neon increased the occurrence of other planes lying parallel to the surface in addition to the major (0 0 0 2) orientation obtained during vacuum evaporation. The microstrain in the films increased with crystallite size. A very small crystallite size was obtained from the vacuum-evaporated coating. In comparison with vacuum evaporation, however, crystallite size was observed to increase significantly with the introduction of either inert gas at 0.33 Pa and then reduce with increasing pressure. It is inferred that the change in crystallite size arises from metal cluster formation in the gas phase; larger clusters are suggested to form in argon. (C) 2003 American Vacuum Society.