Аннотация:We investigated the change in the spectral and kinetic parameters describing the decay of tryptophan fuorescence in an aqueous medium under pulsed photoexcitation as a function of temperature in the range of -170°C to +20°C. A model is proposed and a quantitative analysis of the rates of direct and reverse electronic transitions in the tryptophan molecule from the excited state to the ground state and to the charge transfer state is carried out.