The frontier molecular orbitals （HOMO and NHOMO） of CF2BrCl molecule have been firstly investigated by （e,2e） electron momentum spectroscopy. The experimental momentum profiles are compared with the theoretical profiles employing Hartree-Fock and density functional theory with 6-31G and 6-311+G（d） basis sets. Both HF and DFT calculations using 6-311+G（d） basis set can well describe the experiment, whereas those calculated using 6-31G basis set largely underestimate the experiment at the low momentum region. Furthermore, orbital electron density images show that HOMO and NHOMO have a mixed character of the bromine and chlorine lone pairs.
