The ground-state rotational spectra of two isotopomers 15N2⋯I35Cl and 15N2⋯I37Cl of a complex formed between dinitrogen and iodine monochloride were observed by pulsed-jet, Fourier-transform microwave spectroscopy. The spectra were interpreted on the basis of a linear equilibrium geometry with the weak bond formed between N and I. The spectroscopic constants B0, DJ, χaa(I), χaa(Cl) and Mbb(I) were determined for each isotopomer and various models for the complex were employed to yield the distance r(N⋯I)=3.180(2)Å, the intermolecular stretching force constant kσ=5.37(3)Nm−1, and the inter- and intramolecular electronic transfers δi=0.004(3) and δp(Cl)=0.018(2).