The analysis of the recently recorded 78–378GHz broadband spectrum of ClONO 2 has been extended to cover rotational transitions in all 14 excited vibrational states up to 650cm −1 above the ground state. We report new measurements and analysis of the 2ν 9 and 3ν 9 dyads, and first assignment and analysis for the 4ν 9 and 5ν 9 triads. The polyad fits encompass a total of over 20000 newly measured transition frequencies and spectroscopic constants are reported for 10 vibrationally excited states in each of 35 ClONO 2 and 37 ClONO 2 . All polyads were fitted with a new coupling scheme between the perturbing states combining c-axis Coriolis and Fermi interactions. The scheme is validated by multiple tests of the physical significance of the derived parameters and it results in improved deviations of fits and significant reduction in the number of adjustable parameters.