Based on the normal coordinate theory, the vibrational analysis of the ground state (Bt), the electronically excited state (A2) and singly ionised state (A,) of ClO2 has been carried out and the force constants corresponding to these three states have been evaluated by kinetic constants method employing the general valence force field. These force constants have been used to calculate the mean square amplitudes of vibration, Coriolis Coupling Coefficients and Centrifugal distortion constants of ClO2 in these three states.