This book reviews statistical exciton model of nuclear reactions, and how it is used to calculate Preequilibrium Emission (PE) spectra and reaction cross-sections at energies about 80 MeV. Numerical calculations are made for a two-component system, for (N,N) reactions with Fe-54, Fe-56, Rh-103, and Bi-209 nuclei. Two contributions to the existing model are made: The development of a complete and analytical solution to calculate the state density of excited states based on the one-component non-Equidistant Spacing Model (non-ESM). Also, a simple numerical approach to solve the master equation at energies less than 80 MeV is presented. A variety of quantities required during PE calculation, such as the state density of the excited states, the effective matrix element of the specified reaction, the occupation probability of exciton states, and others are discussed and numerically calculated using a library of MATLAB codes written for this purpose. PE spectra for selected reactions are numerically calculated and compared with earlier calculations.