Abstract: CF _3 CF = CF _2 is a potential source of atmospheric trifluoroacetic acid (CF _3 C(O)OH). The kinetics of the reaction of the simplest Criegee intermediate (CH _2 OO) with CF _3 CF = CF _2 was studied by using the OH laser-induced fluorescence method. At 10 torr, the rate coefficients were measured to be (1.45 \pm 0.14) \times 10 ^-13 , (1.18 \pm 0.11) \times 10 ^-13 , (1.11 \pm 0.08) \times 10 ^-13 , and (1.04 \pm 0.08) \times 10 ^-13 cm ^3\cdot molecule ^-1\cdot s ^-1 at 283, 298, 308 and 318 K, respectively. The activation energy of ( - 1.66 \pm 0.21) kcal/mol was derived from the Arrhenius equation. No obvious pressure dependence was observed.