The highest occupied molecular orbital (HOMO) of chlorotrifluoromethane (CF3Cl) has been studied by binary (e,2e) electron momentum spectroscopy (EMS) for the first time. Impact energy of 1200 eV plus binding energy and symmetric non-coplanar geometry are employed. The experimental momentum profile of HOMO is compared with Hartree-Fock (HF) and density functional theory (DFT-B3LYP) calculations. An outer-valence Green's function (OVGF) calculation of ionization potentials of outer-valence orbitals has also been carried out and compared with previous MSXalpha calculations and photoelectron spectroscopy (PES) measurements.