Several low J microwave transitions of CF 3NO 2 have been measured under high resolution using a pulsed-nozzle Fourier transform spectrometer. The 14N quadrupole coupling constants in the inertial axis system have been accurately determined as eQq aa = −0.641(2) MHz, eQq bb = 0.327(6) MHz and eQq cc = 0.314(6) MHz. These measurements were made in the light of renewed interest in the internal rotation dynamics of CF 3NO 2. The quadrupole coupling constants provide a probe of the bonding at nitrogen. The measured values are consistent with those known for CH 3NO 2, thus providing further evidence for an effective planar geometry of the CNO 2 grouping in CF 3NO 2.