The reaction of O(P-3) with CHFCl2 has been studied using ab initio molecular orbital theory. Two nearly degenerate transition states of (3)A" and (3)A' symmetries were located for this reaction. The kinetic nature is obtained using canonical variational transition state theory with small-curvature tunneling correction method. The calculated rate constants exhibit typical non-Arrhenius behavior, a three-parameter rate-temperature formula is fitted as follows: k(T) = 2.627 x 10(-22) T-3.55 exp(-2525.56/T) cm(3) molecule(-1) s(-1) over a wide temperature range of 200-3000 K. The calculated results match well with the experimental values. (C) 2003 Elsevier Science B.V. All rights reserved.