Mass analyzed threshold ionization (MATI) spectroscopy was used to record the cationic spectra of 2-aminopyridine (2AP) via the 0(o) vibrationless and the 6a(1), 1(1), 1(2), and 18a(1) vibrational levels of the S-1 state. The adiabatic ionization energy of this molecule was determined to be 65411 +/- 5 cm(-1) (8.1095 +/- 0.0006 eV). The experimental findings show that the molecular geometry and vibrational features of the 2AP cation resemble those of the neutral species in the S, state, which is well supported by the ab initio and density functional calculations. (C) 2002 Elsevier Science B.V. All rights reserved.