After slaughter, the muscle cells undergo biochemical and physicochemical changes which may affect their autofluorescence characteristics. The postmortem metabolism kinetic of rat EDL and soleus muscles was assessed by glycogen depletion determination while autofluorescent response of different muscle fiber types was investigated by Deep UV synchrotron microspectroscopy at slaughter and and 24 hours postmortem. Following a 275 nm excitation, emission fluorescence spectra showed discrimination depending on postmortem time (T0 versus T24h) on both muscles at 346 and 302 nm and to a lesser extent at 408 and 325 nm. Taken individually, all fiber types are discriminated but with variable accuracy, the type IIA showing better separation of T0 comparing to T24h than other fiber types. These results highlight the relevance of using the autofluorescent response of muscle cells to rapidly assess their state of postmortem changes.