The first high resolution infrared spectrum of the ionic complex N-2.. H+.. N-2 and its deuterated derivative is reported. The spectra were obtained in direct absorption in a supersonic slit nozzle plasma. The observed rovibrational transitions were assigned to the nu(3) antisymmetric NN stretching vibration and the spectrum is consistent with a linear centrosymmetric equilibrium structure. The band origin is found at 2352.2364(6) cm(-1) and the ground state rotational constant is determined as B"=0.081 809(14) cm(-1). The assignment is supported by ab initio calculations including electron correlation effects. The best estimate for the equilibrium structure is R-e (NN) = 1.095 Angstrom and re (N .. H) = 1.277 Angstrom. The transition moment of the nu(3) band of N-2.. H+.. N-2 is predicted to be 0.21 D, an order of magnitude larger than for the NN stretching vibration of HN2+. The equilibrium dissociation energy D-e for fragmentation into N-2 and HN2+ is calculated to be similar to 5900 cm(-1).