The reaction of NO2 with CzF4 was studied at 30Β°, 68", 114O, and 157Β°C by in situ monitoring the infrared absorption bands of the products. The major primary products of the reaction are OzNCFzCFO and FNO. Smaller amounts of CFZO (and presumably NO) are also produced. There was no evidence for other primary products, though they may have been produced in minor amounts. The rate laws for the production of both O Z N C F ~C F O and CFzO are first order in both " 0 2 1 and [CzFd]. CFzO production is at least partly heterogeneous as demonstrated by packing the quartz reaction vessel with Pyrex beads and by using a Monel cell. The homogeneous rate constant obtained from the high-temperature results gives a rate constant of 3.4X108 exp (-17000/RT) M-lsec-l for CFzO production. Actually these Arrhenius parameters represent lower limits, since the heterogeneous reaction may still be playing a significant role. The production rate of 0 2 N C F z C F 0 is not much affected by changing the nature of the surface or the surface to volume ratio. However the reaction may be heterogeneous, since the rate constant for its formation of 1.3 X lo4 exp ( -7500/R T ) A4-lsec-l has an abnormally low preexponential factor. Experiments in the presence of N O indicate that the mechanism for O Z N C F ~C F O formatlon is (1 1) (12) NO2 + CzF4 -+ OzNCFzCFz OJ'JCFzCFz + NO2 -+ 0zNCFzCFO + FNO The intermediate can also react with NO: (13) OzNCFzCFz + NO + OzNCFzCFzNO with k13/k12 = 1.3.