A chirped pulse Fourier transform microwave spectrometer was used to obtain pure rotational spectra for CF 3CF 2Cl between 8 GHz and 16 GHz, and for CF 3CF 2Br between 8 GHz and 14 GHz. in both cases rotational constants, quartic centrifugal distortion constants and chlorine/bromine nuclear electric quadrupole coupling tensors were obtained for the first time. For both compounds only the trans conformer was observed. Quantum chemical calculations have provided structures with rotational constants closely matching the experimental values. For CF 3CF 2Br the spectra collected were sufficiently strong that the C-13 isotopologues could be observed in natural abundance. Δ J = 2 transitions were observed in the rotational spectrum of CF 3CF 2Br, but were not observed in the spectrum for CF 3CF 2Cl.