Magnetic circular dichroism spectroscopy (MCD) has been used to assign the optical spectra in high- and low-symmetry molybdenyl complexes. High-resolution single crystal polarized absorption spectra of [PPh(4)][MoOCl4] and [AsPh(4)][MoOCl4(H2O)] show two ligand field transitions whose polarization, MCD, and vibronic fine structure are compatible with the previously accepted assignments (2)E <-- B-2(2) (15000 and 13000 cm(-1), respectively) and B-2(1) <-- B-2(2) (23000 cm(-1) in both). In the case of [AsPh(4)][MoOCl4(H2O)], the splitting of the (2)E by spin-orbit coupling is clearly visible and a spin-orbit coupling constant of 810(2) cm(-1) has been measured. At higher energies, four charge transfer transitions arising from nonbonding chloride orbitals to the metal d(xy) orbital have been identified.