Abstract The vibrational frequencies and corresponding normal mode assignments of dewar benzene are examined theoretically using the gaussian 98 set of quantum chemistry codes. All normal modes were successfully assigned to one of six types of motion predicted by a group theoretical analysis (C–H stretch, C–C stretch, CC stretch, CH wag, C–C–C bend, and C–C–C–C torsion) utilizing the C 2v symmetry of the molecule. The molecular orbitals and bonding of dewar benzene are examined. Predicted normal mode frequencies for trans -dewar benzene ( C 2h symmetry) are presented.