This work deals with an acquiring system dedicated to the measurement of the resonance frequency and the quality factor of organic piezoelectric resonators. These resonators consist of a free-standing cantilever and its non-released counterpart used to compensate electrical signals that are not due to mechanical behavior. The system uses a capacitive half-bridge with two AC voltages in opposite phases, associated with an IQ demodulator. The magnitudes of the two AC voltages can be set independently from one another, which enables a powerful compensation of parasitic capacitance. Thanks to this dedicated system, measurements of the resonance frequency of organic piezoelectric resonators both in air and liquid media have been performed. Several methods to determine accurately the resonance frequency have been tested and compared in terms of measurement noise.