The normal coordinate calculations of the complex of SbF5with SO2have been carried out for the CSsymmetry on a modified Urey-Bradley force field. The defined force constants have been adjusted to reproduce the observed fundamental frequencies reported by Byler and Shriver. The potential energy distribution matrix elements have also been calculated for the symmetry co-ordinates to confirm the tentative assignments. The coordination effects on the bond nature of the complex have been discussed using the obtained constants.