FTIR smog chamber techniques have been used to show that reaction of CF3O2, radicals with NO proceeds via two channels giving either CF3O + NO2 (5a) or CF3ONO2 (5b) as products. In 700 Torr of N-2/O-2 diluent at 296 K the branching ratio for CF3 ONO2, formation is k(5b)(k(5a) + k(5b)) = (1.67 +/- 0.27) x 10(-2). The CF3ONO2, forming channel is in the fall off regime at pressures of 50 Torr and below, while for pressures above 100 Torr the reaction approaches the high-pressure limit. This behavior is consistent with the predictions of recent master equation calculations [Chem. Rev. 103 (2003) 4577]. (C) 2004 Elsevier B.V. All rights reserved.