Boron triazide, B(N-3)(3), is first generated in gas phase by the heterogeneous reaction of BBr3 vapor with freshly synthesized AgN3 powder at room temperature. Identification of B(N-3)(3) has been achieved by combination of photoelectron spectroscopy with the outer valence Green's function calculation. B(N-3)(3) is a planar molecule with C-3h, symmetry and has the first adiabatic ionization energy of 11.39 eV. Vibrational spacings 2200 +/- 60 cm(-1) and 1250 +/- 60 cm(-1) on the first and third bands match well to the N-3 asymmetric stretch and the B-N stretching vibrations in the neutral B(N-3)(3) molecule, respectively. (c) 2005 Elsevier B.V. All rights reserved.