The reaction of O((3)p) with silane was studied theoretically. The detailed mechanism was revealed for the first time. Two nearly degenerate transition states of 3A" and 3A' symmetries were located for the title reaction. Geometries were optimized at the UMP2 level with the 6-311G(2d,2p) basis set. The QCISD(T) level with the 6-311++G(3df,3pd) basis set was used in the final single-point energy calculations. On the basis of the ab initio data, the kinetic nature was studied using canonical variational transition-state theory (CVT) with small-curvature tunneling effect (SCT) correction. The rate constants were calculated over a wide temperature ran-e of 200-3000 K. The CVT/SCT rate constants exhibit typical non-Arrhenius behavior, a three-parameter rate-temperature formula was fitted as follows: k(7 = (1.53 x 10-(17))T-2.25 exp(-834.32/T) (in units of cm(3) molecule(-1)s(-1)). The calculated CVT/SCT rate constants match wetl with the experimental values.