The kinetics of the chemical vapor deposition of tungsten by the hydrogen reduction of WF 6 were studied over the system pressure range from 6 to 60 Torr and over the temperature range from 500° to 870°C to determine the operative rate controlling mechanisms. Within the pressure and temperature ranges studied HF desorption from the substrate was determined to be rate limiting for lower pressure‐temperature combinations. An activation energy of 7300 cal/mole was associated with this mechanism. At higher pressure‐ temperature combinations WF 6 diffusion to the substrate was rate controlling. The activation energy for this process was found to be 1650 cal/mole.