The acquisition of signals from liquid scintillators with Flash ADC of high sampling rate (1 GS / s ) has been investigated. The possibility to record the signal waveform is of great advantage in studies with γ's and neutrons in a high count-rate environment, as it allows to easily identify and separate pile-up events. The shapes of pulses produced by γ-rays and neutrons have been studied for two different liquid scintillators, NE213 and C₆D₆. A 1-parameter fitting procedure is proposed, which allows to extract information on the particle type and energy. The performance of this method in terms of energy resolution and n/γ discrimination is analyzed, together with the capability to identify and resolve pile-up events.