In this gas-phase photoelectron spectroscopy study, we present the electron binding energy spectrum and photoelectron angular distributions of NbN- by the velocity-map imaging technique. The electron binding energy of NbN- is measured to be 1.42 +/- 0.02 eV from the X band maximum which defines the 0-0 transition between ground states of anion and neutral. Theoretical binding energies which are the vertical and adiabatic detachment energies are computed by density functional theory to compare them with experiment. The ground state of NbN- is assigned to the (2)Delta(3/2) state and then the electronic transitions originating from this state into X-3 Delta(Omega) (Omega = 1-3), a(1)Delta(2), A(3)Sigma(-)(1), and b(1)Sigma(+)(0) states of NbN are reported to interpret the spectral features. As a prospective study for catalytic materials, spectral features of NbN- are compared with those of isovalent ZrO- and Pd-. Published by AIP Publishing.