Long path length FTIR-smog chamber techniques were used to study the title reactions in 700 Torr of N₂, oxygen or air diluent at 296 ± 2 K. Values of k(Cl + CF₃CN) = (2.43 ± 0.33) × 10⁻¹⁵ and k(OH + CF₃CN) = (4.61 ± 0.34) × 10⁻¹⁵ cm³ molecule⁻¹ s⁻¹ were measured. There was no discernible reaction of CF₃CN with O₃ and an upper limit of k(O₃ + CF₃CN) ≤ 7.9 × 10⁻²⁴ cm³ molecule⁻¹ s⁻¹ was established. The IR spectra of CF₃CN and CF₃CF₂CN are reported. The atmospheric lifetime of CF₃CN is determined by the reaction with OH and is approximately 6.9 years. Reaction of CF₃CN with Cl atoms in a chamber study gives (Z-) and/or (E-) CF₃CCl[double bond, length as m-dash]NCl and CF₃C(O)Cl as major primary products. Under environmental conditions, the OH radical initiated oxidation gives COF₂ in a yield of (96 ± 8)%. The global warming potential for CF3CN is estimated as 1030 for a 100 year time horizon.