Indium tin oxide thin films consisting mainly of whiskers have been deposited on glass by electron beam evaporation. Low deposition rates (35 Å/min) and substrate temperatures in the 120-400 °C range were used. Morphology by scanning electron microscopy, crystal structure, energy dispersive analysis of x-rays, and x-ray photoelectron spectroscopy compositions, optical and conducting properties of films have been studied as a function of temperature of growth and further annealing in air. Whiskers associate and produce flatter surfaces, the grain size increases from ≈390 Å to ≈790 Å, keeping however its fibrous structure after 400 °C-30 min annealing. In films deposited at temperatures below 200°C, next to cubic In2O3, tetragonal Sn and cubic In2Sn2O(7-x) appear. During growth and after air annealing Sn4+ segregates to the surface, attaining Sn/In concentration ratios of 4.6. On air annealing the optical transmittance and electrical resistance increase, in some cases from 2% to 90% and by a factor of about 4, respectively. © 1998 American Institute of Physics.