Hydrogenation of silicon tetrachloride (STC) in the presence of silicon was investigated both thermodynamically and experimentally. The thermodynamic results revealed that the reaction is thermodynamically constrained and the STC equilibrium conversion is nearly temperature-independent but increases with increasing pressure and H-2/STC feed ratio. Trichlorosilane (TCS) was calculated to be the dominant product, with trace amounts of dichlorosilane (DCS) and HCl as feasible byproducts. Experimental tests were conducted in a fixed-bed reactor loaded with silicon. The results indicated that the reaction is kinetically restricted in the absence of a catalyst. Adding CuCl to the silicon mass bed was found to result in a dramatic increase in the STC conversion, and Cu3Si was determined to be the active species. In all of the tests runs, TCS was determined to be the dominant product, and the STC reaction rate was found to increase markedly as the temperature and STC partial pressure increased but not to depend on the silicon particle size.