The development of a multipass optical absorption (MPA) technique for detecting CF2 radicals behind reflected shock waves and its application for studying the thermal dissociation of CF2HCl in Kr are reported. In an earlier work, a Cl atom atomic resonance absorption spectrometric (ARAS) study on the thermal decomposition of CF2Cl2 gave the stoichiometric yield of two Cl atoms per dissociating CF2Cl2, indicating the overall process is CF2Cl2 = 2Cl + CF2. CF2 yields with CF2Cl2 as the thermal source were then used to obtain the CF2 curve of growth. The effective absorption cross section is 2.86 × 10-18 cm2 at 249.8 nm. In the CF2HCl experiments, the yield was measured to be 1.01 ± 0.06, confirming that the thermal decomposition pathway is molecular HCl elimination; i.e., CF2HCl (+ M) → CF2 + HCl (+ M). Above 1900 K, C−Cl bond fission was measured to be <1%. Rate constants for the title reaction were measured by observing the temporal formation of CF2 radicals. Also, rate constants were measured and the ove...