Abstract : Reverberation chambers are widely used in electromagnetic compatibility, they allow to perform immunity testings and total radiated power measurements. They are generally used in the frequency domain. This work gives a theoretical and experimental study of the behavior of the reverberation chambers in the time domain and in the frequency domain in order to perform immunity testings. We choose to develop a numerical model based on image theory to describe the behavior of a reverberation chamber in time domain. Unlike numerical methods like FDTD, TLM or the method of moments, image theory allows to describe a rectangular cavity without sampling its surface or its volume. The model takes into account the dimensions of the cavity, the position of the emitting antenna in the cavity and the losses introduced by the walls, the antennas and any object in the cavity. The model allows a description of the behavior of a reverberation chamber in both the time domain and the frequency domain. We show that the waveforms simulated are similar with the waveforms measured in a real reverberation chamber. From a statistical point of view, we show that the model is able to reproduce the statistical behavior of a chamber used in ideal regime as well as non-ideal regime when the reverberation chamber is under-moded. We study the spatial correlation of the electric field and we show that the spatial correlation of the fields simulated is in agreement with theory. The numerical model is used to study immunity testings. We try to measure the relative performances of immunity testings performed with a random electric field (in a reverberation chamber for example) and with plane waves (in an anechoic chamber or a GTEM cell) for different devices under test. We propose a new method to measure the susceptibility of a device in a reverberation chamber. We try to optimize immunity testings in order to increase the efficiency and reduce the duration of the testings in a reverberation chamber. Finally, we propose a modus operandi to perform immunity testings with pulsed signals in a reverberation chamber and we focus on the reproduction of a real life illumination with radar pulses in a reverberation chamber.