The quantum-chemical study of spectral and photophysical properties of indole by the Intermediate Neglect of Differential Overlap (INDO) method is carried out. The rate constants of radiative degradation kr, internal transition kin, and intercombination conversion kST are calculated. Various models of the indole molecule in neutral and aqueous solutions at low temperature are considered. The obtained results agree well with experimental data. In aqueous solutions, the indole absorption and fluorescence bands are shifted toward longer waves relative to neutral solutions.