NOVELTY - Making trihalosilane, involves: contacting an organotrihalosilane comprising hydrocarbyl trihalosilane with hydrogen, at mole ratio of 0.009:1 to 1:2300, in presence of catalyst comprising metal selected from rhenium; mixture comprising rhenium and palladium, ruthenium, manganese, cupper, and/or rhodium; mixture of iridium and palladium and/or rhodium; manganese; mixture comprising manganese and rhodium; silver; magnesium; and rhodium, at 300-800 degrees C to form trihalosilane.    USE - For making trihalosilane (claimed), which is useful for making high purity polycrystalline silicon, which is useful in solar cells or electronic chips, or polycrystalline silicon is hydrolyzed to produce polysiloxanes, which is useful in many industries and applications.    ADVANTAGE - The method provides improved method for producing trihalosilanes, such as trichlorosilane; as compared to the prior art methods, which employ zero-valent silicon as zero-valent silicon is produced by highly energy-intensive carbothermic reduction of silicon dioxide, thus using it directly adds costs to these processes. The method produces trihalosilane from hydrogen and organotrihalosilane. Since the method does not directly employ zero-valent silicon to make trihalosilane, the method is more economical and requires less energy than other methods in art for producing trihalosilane. The method has combined selectivity for making trihalosilane and dihalosilane of at least 50 wt.%, based on total weight of all silanes made in the contacting step.    DETAILED DESCRIPTION - Making a trihalosilane, involves: contacting an organotrihalosilane of formula R'SiX'3 (I), with hydrogen, where the mole ratio of the organotrihalosilane to hydrogen is 0.009:1 to 1:2300, in the presence of a catalyst comprising a metal selected from Re; mixture comprising Re and at least one element selected from Pd, Ru, Mn, Cu, and Rh; a mixture comprising Ir and at least one element selected from Pd and Rh; Mn; a mixture comprising Mn and Rh; Ag; Mg; and Rh, at 300-800 degrees C to form a trihalosilane of formula HSiX'3.    R'=1-10C hydrocarbyl;    X'=halo.