A deterministic identifiability analysis of kinetic models of two-state excited-state processes in the presence of transient effects is performed to establish the conditions for the unique determination of the excited-state species deactivation rate constants with no assumption regarding the kinetics of interconversion in the excited state. It is necessary that decays of at least one excited-state species can be monitored separately to uniquely determine the excited-state species deactivation rate constants. This conclusion holds for reversible and irreversible intermolecular as well as intramolecular excited-state processes in the presence of transient effects. Sufficient conditions for the recovery of the deactivation rate constants are established for several cases of practical relevance.