The outer valence electron binding energies and the fundamental gap of p-nitroaniline (PNA) in water were determined by electron propagator theory. The adopted methodology relies on the calculation of electron binding energies by using configurations generated by Born-Oppenheimer molecular dynamics of PNA in water. The fundamental gap (E-g) of PNA in water was estimated from the first ionisation energy (IE) and the first vertical electron affinity VEA (E-g = IE-VEA). In liquid water E-g is predicted to be 6.5 +/- 0.5 eV (OVGF), which is similar to 3.3 eV greater than the experimental optical gap (3.25 eV). (C) 2016 Elsevier B.V. All rights reserved.