Résumé : A study of the n-γ discrimination with NE213 and BC501A liquid scintillators, carried out with 40 and 56 MeV neutron beams, reflects different reaction channels involved in the detection process of high energy neutrons. Up to seven different reaction channels were identified in the pulse shape discrimination spectrum measured by a digital charge comparison method. The analysis of the energy spectra of the secondary particles allowed the cross sections for different reaction channels to be estimated as well. This is shown for the important 12C(n, d) reaction and the non-negligible contribution of the 12C(n, t) reaction to the total efficiency of the NE 213 liquid scintillator for neutrons.