An analytical model is presented to describe time-of-flight (TOF) peak shapes of ionized metastable species emitted from solid surfaces under particle or photon bombardment. The model complements and consolidates the formalism for determination of metastable ion mean lives, release energies (Q-values), and fragmentation patterns by using linear-type TOF spectrometer data. Effects of fragmentation in the field free region of the TOF spectrometer are discussed. The analysis of phenylalanine TOF spectrum is performed to illustrate the determination of Q and mean life values.