For intermediate energies in the range of 20–100 MeV/A, multifragmentation is the one of the nuclear mechanisms which determine variety of reaction products. Moreover, emission of secondary fragments is strongly dependent on excitation energy of hot nuclear sources. As a results of heavy ion collisions at intermediate energies, high excited nuclear matter is produced. Time evolution of such system is a very dynamic process, so experimental detection of primary nuclear fragments is impossible at this stage. De-excitation of this matter, through the secondary decays produces a variety of stable fragments which can be measured in the experiments. This phenomenon causes that information about the original nucleus from which are formed secondary particles can be lost. We propose a reconstruction procedure based on correlations between intermediate mass fragments and multiplicities of light particles like: n, p, d, t, 3He, 4He. Secondary
products of heavy ion reaction have been obtained by predictions given by the GEMINI model. A combination of theoretical knowledge with experimental data, especially information about secondary fragments and average
excitation energy, allows to obtain a reaction products formed directly after heavy ion collision.