Description and results of investigations in the process area of trichlorosilane (TCS) production being the raw material for polycrystalline silicon productions are presented. Laboratory-scale plant for low-temperature hydrogenating of silicon tetrachloride is described. Conducted researches are directed on solving the problem of conversion of silicon tetrachloride, forming in large amounts and with direct synthesis of TCS as well as in production of polycrystalline silicon. The value of specific speed of the process of low-temperature hydrogenating of silicon tetrachloride, accompanying by achieving of maximum content of TCS attaining in synthesized steam-gas mixture is estimated.