A combined experimental and theoretical study of the charge-transfer complex [Ar–N2]+∙ is presented. Nearly 50 transitions split by spin-rotation interaction have been observed by means of infrared diode laser absorption spectroscopy in a supersonic planar plasma expansion. The band origin is at 2272.2563(18)cm−1 and rotational constants in the ground and vibrationally (NN-stretch) excited state amount to 0.128701(8)cm−1 and 0.128203(8)cm−1, respectively. The interpretation of the data in terms of a charge switch upon complexation is supported by new ab initio calculations. The best estimate for a linear equilibrium structure yields Re(NN)=1.102Å and Re(Ar–N)=2.190Å. Predictions for molecular parameters not directly available from the experimental results are presented as well. Furthermore, the electronic structure and Ar–N bonding mechanism of [Ar–N2]+∙ have been analyzed in detail. The Ar–N bond is a textbook example of a classical 2-center-3-electron bond.