The gas phase structure of O-nitrobis(trifluoromethyl)hydroxylamine, (CF3)(2)NONO2, has been determined with gas electron diffraction and quantum chemical calculations (HF, MP2, and B3LYP with 6-31G* basis sets). The calculations predict a structure with C, overall symmetry, a planar NONO2 skeleton, and the NO2 group oriented anti with respect to the CNC plane. The electron diffraction intensities are reproduced very well with such a model. The molecule possesses pyramidal configuration at the amino nitrogen atom, and the following geometric parameters (r(a) values with 3sigma uncertainties) were obtained for the NONO2 skeleton: N-O = 1.392(18) Angstrom, O-N = 1.597(16) Angstrom, (N=O)(mean) = 1.192(4) Angstrom, N-O-N = 106.9(25)degrees, O=N=O = 138.4(24)degrees. The extremely long O-N distance is rationalized by very weak bonding between the two stable radicals (CF3)(2)NO and NO2. Whereas the ab initio methods HF (O-N = 1.395 Angstrom) and MP2 (O-N = 1.664 Angstrom) fail to reproduce this bond length correctly, the hybrid method B3LYP (O-N = 1.584 Angstrom) results in good agreement.