In this paper, the properties of low pressure chemically vapor deposited tungsten silicide films processed from tungsten chlorides and silane are studied as a function of hydrogen initial partial pressure. By means of thermodynamic calculations, we have defined a priori the operating conditions leading to each silicide deposition. The corresponding films are grown in a cold-wall reactor and characterized by x-ray diffraction and scanning electron microscopy studies. Good agreement between theoretical and experimental results is obtained. The increase of initial hydrogen partial pressure has two possible consequences : a modification of the film composition for high WCl4 partial pressure and a modification of the film growth rate for lower WCl4 partial pressure.