Abstract The high-resolution gas-phase Fourier transform infrared spectrum of the linear molecule isocyanogen, CNCN, has been measured between 150 and 1300 cm −1 with an unapodized resolution of 0.0018 cm −1. The band systems due to the excitation of the cis and trans bending modes ν 5 and ν 4 around 194.8 and 463.5 cm −1, respectively, have been analyzed. Additionally the combination band system ν 5 and ν 4 around 659.0 cm −1 and the transitions to the Fermi resonance pair ν 3 and 2ν 4 around 875 and 975 cm −1, respectively, were analyzed. Furthermore, two components of the related Fermi triad could be assigned. Constants of a power series in J( J + 1) for the numerous subbands as well as constants of an effective Hamiltonian (K. M. T. Yamada, F. W. Birss, and M. R. Aliev, J. Mol. Spectrosc. 112, 347-356, 1985) are presented.