This study investigated the hydrogenation of silicon tetrachloride (SiCl

4

) in microwave plasma. A new launcher of argon (Ar) and hydrogen (H

2

) plasma was introduced to produce a non-thermodynamic equilibrium activation plasma. The plasma state exhibited a characteristic temperature related to the equilibrium constant

which was termed "Reactive Temperature" in this study. Thus

the hydrogenation of SiCl

4

in the plasma could easily be handled with high conversion ratio and very high selectivity to trichlorosilane (SiHCl

3

). The effects of SiCl

4

/Ar and H

2

/Ar ratios on the conversion were also investigated using a mathematical model developed to determine the optimum experimental parameters. The highest hydrogenation conversion ratio was produced at a H

2

/SiCl

4

molar ratio of 1

with mixtures of SiCl

4

and H

2

to Ar molar ratio of 1.2 to 1.4. In this plasma

the special system pressure and incident power were required for the highest energy efficiency of hydrogenating SiCl

4

while the optimum system pressure varies from 26.6 to 40 kPa depending on input power

and the optimum feed gas (H

2

and SiCl

4

) molar energy input was about 350 kJ·mol

-1

.