The C2Cl3 --> C2Cl2 + Cl (1) reaction was studied using the laser photolysis/photoionization mass spectrometry technique. Rate constants were determined in time-resolved experiments as a function of temperature (569683 K) and bath gas density ([He] = (3-24) x 10(16) atoms cm(-3), [N-2] = 12 x 10(16) molecules cm(-3)). C2Cl2 was observed as a primary product of reaction 1. Rate constants of reaction I are in the falloff, closer to the low-pressure limit, under the conditions of the experiments. The potential energy surface (PES) of reaction 1 was studied using a variety of quantum chemical methods. The results of the PES study indicate that the minimum energy path of the C2Cl3 dissociation proceeds through a shallow-well symmetric structure with the departing Cl atom equidistant from both carbon atoms; a PES saddle point exists between the nonsymmetric equilibrium C2Cl3 structure and the symmetric one. The results of quantum chemical calculations and the experimental rate constant data were used to create a model of reaction 1. The experimental dependence of the rate constant Of C2Cl3 decomposition on temperature and pressure was reproduced in RRKM/master equation calculations. The reaction model provides expressions for the temperature dependences of the high-pressure-limit and the low-pressure-limit rate constants and the falloff broadening factors: k(1)(infinity) = (1.36 x 10(13))T-0.29 exp(-13625 K/T) s(-1), k(1)degrees(He) = (4.89 x 10(12))T6.14 exp(-14497 K/T) cm(3) molecule(-1) s(-1), k(1)degrees(N-2) = (1.525 x 10(12))T-5.95 exp(-14393 K/T) cm(3) molecule(-1) s(-1), F-cent(He) = 0.33 exp(-T/1836 K) + 0.67 exp(-T/98 K) + exp(-3650 K/T), and F-cent(N-2) = 0.35 exp(-T/1864 K) + 0.65 exp(-T/103 K) + exp(-3614 K/T). The experimental data are not sufficient to specify all the parameters of the model; consequently, some of the model parameters were obtained from quantum chemical calculations and from analogy with other reactions of radical decomposition. Thus, the parametrization is most reliable under conditions close to those used in the experiments.