The hydrogen abstraction reaction of atomic O (P-3) with CH2FCl has been studied theoretically for the first time. Geometries have been optimized at the MP2 level with the 6-311 G(d, p) basis set. Energies along the minimum energy path have been improved by a series of single-point ab initio G3(MP2)HMP2/6-311G(d,p) calculation. The rate constants are obtained using canonical variational transition state theory (CVT) with small-curvature tunneling (SCT) correction method over a wide temperature range of 200-3000 K. The calculated results are compared with the available experimental values. (C) 2003 Elsevier B.V. All rights reserved.