The conformational properties and geometric structure of tris(2,2,2-trifluoroethyl)amine, N(CH2CF3)(3), have been determined for the gaseous and solid state by electron diffraction and X-ray crystallography, respectively. In the gas phase the predominant conformer possesses C-1 symmetry, and small contributions of C-s (<25%) and/or C-3 (<10%) conformers cannot be excluded. In the crystal, however, the molecule adopts a structure with C-3 symmetry. Raman spectra at temperatures between +24 and -35 degrees C demonstrate the presence of a mixture of at least two conformers in the liquid phase. The following geometric parameters (r(a) distances and angle(alpha) angles with 3 sigma uncertainties) were derived for the nitrogen-carbon skeleton in the gas phase : N-C = 1.436(6) Angstrom, C-C = 1.527(5) Angstrom, CNC = 116.6(9)degrees, (NCC)(mean) = 113.7(9)degrees, Phi(1) = 180 degrees (ass), Phi(2) = 10.8(11)degrees, and Phi(3) = 19.4(11)degrees. Phi(i) are the lp-N-C-C dihedral angles (lp = nitrogen lone pair). The corresponding parameters for the crystal structure (mean values with sigma uncertainties) are very similar : N-C = 1.453(3) Angstrom, C-C = 1.507(3) Angstrom, CNC = 115.1(2)degrees, NCC = 111.6(2)degrees, and Phi(i) = 22.1(3)degrees. According to ab initio calculations CHF/3-21G with polarization functions at nitrogen), the most stable structure possesses C-1 symmetry and the C-s and C-3 conformers are higher in energy by 0.7 and 3.6 kcal/mol, respectively.