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The direct hydrogen abstraction reactions of H atoms with SiH3Cl, SiH2Cl, and SiHCl3 have been studied systematically using ab initio molecular orbital theory. Geometries have been optimized at the UMP2 level with the 6-311 G(2d, p) basis set. The G3MP2 theory has been used for the final single-point energy calculation. Theoretical analysis provides conclusive evidence that the main process occurring in each case is the hydrogen abstraction from the Si-H bond; the chlorine abstraction from the Si-Cl bond has a higher barrier and is difficult to react. Changes of geometries, generalized normal-mode vibrational frequencies, and potential energies along the reaction path of the reactions are discussed and compared. The kinetic calculations of the title reactions have been deduced using canonical variational transition state theory (CVT) with the small-curvature tunneling (SCT) correction method over a wide temperature range of 200-3000 K. The CVT/SCT rate constants exhibit typical non-Arrhenius behavior. Three-parameter rate -temperature formulas have been fitted as follows: k(1) = 1.54 x 10(-20)T(3.03) exp(-269.39/T), k(2) = 1.93 x 10(-19)T(2.62) exp(-453.05/T), and k(3) = 3.13 x 10(-1)9T(2.30) exp(-249.99/T for the reactions of H with SiH3Cl. SiH2Cl2, and SiHCl3, respectively (in units of cm(3) molecule(-1) s(-1)). Studies show that chlorine substitution has no noticeable effect on the strength and on reactivity of the Si-H bond in SiH4-nCln (n = 1-3). The calculated CVT/SCT rate constants are in excellent agreement with the available experimental values.