The hydrogen abstraction reaction of SiH2O2 With O (P-3) has been studied theoretically for the first time. Two transition states of (3)A" and (3)A' symmetries have been located for this abstraction reaction. Geometries have been optimized at the MP2 level with the 6-311G(2d,p) basis set. A modified G3MP2 method has been used for the final single-point energy calculation. On the Basis of the ab initio data, the rate constants have been deduced over a wide temperature range of 200-3000 K using canonical variational transition-state theory (CVT) with small curvature tunneling effect (SCT)., The calculated rate constants have been compared with the experimental values. (C) 2003 Elsevier Science B.V. All rights reserved.