We present time-resolved photoelectron spectra in combination with quantum chemical calculations based on time-dependent density functional theory for the study of the long-lived excited state of Au6−. The experimental spectra indicate an excited state lifetime of at least 90 ns. It is shown that the orbital symmetry of the photoexcited state as well as the planarity of Au6− are responsible for the unusual long lifetime. A possible decay mechanism is the fluorescence of a photon which is estimated to take place on a time scale of 730 ns.