Fourier transform infrared spectroscopy was used to identify CH2FOOH and HC(O)F as products of the gas-phase reaction of CH1FO2 radicals with HO2 radicals. At 700 Torr and 295 +/- 2 K, branching ratios for the CH1FOOH forming channel, k(1a)/k(1) = 0.29 +/- 0.08 and the HC(O)F channel, k1b/k1 = 0.71 +/- 0.11 were established. Quoted errors are 2 standard deviations together with our estimate of systematic uncertainties. This result is discussed with respect to previous literature data and to computer models of atmospheric chemistry. As part of this work, the reactivity of Cl atoms towards CH2FCl and CH2FOOH was investigated; rate constants of k(Cl + CH2FCl) = (1.1 +/- 0.1) X 10(-3) and k(Cl + CH2FOOH) = (1.5 +/- 0.5) X 10(-3) cm(3) molecule(-1) s(-1) were determined.