The equilibrium geometry and harmonic vibrational frequencies of Rn . NO+ are calculated at the QCISD level of theory, employing an effective core potential augmented by a large, flexible diffuse and polarization valence space. The interaction energy is then calculated at the CCSD(T) level using a larger basis set based on a different ECP. The trends in the bonding in the Rg . NO+ complexes (Rg = rare gas) are then noted, and it is confirmed that the major interaction in these species is the charge/induced-dipole interaction.