The manifestations of slow dissociation reactions of singly charged ions in one- and two-dimensional time-of-flight mass spectra recorded on a reflection spectrometer are described and illustrated. These slow reactions produce metastable signatures in both photoelectron—photoion coincidence spectra (PEPICO) and photoelectron—photoion—neutral coincidence spectra (PEPINCO) that give limited information on ion lifetimes, kinetic energy releases and decay pathways. An empirical formula is given for the position of the metastable peaks in time-of-flight (PEPICO) spectra.