This paper investigates the acoustic wave formation processes inside an excimer laser system. Accurate discharge stability diagnostics achieved with a fast CCD camera and a piezoelectric pressure probe show a strong correlation between the electric arcs appearing during the discharge and the acoustic waves created in excimer laser devices. This experimental result is confirmed by a simple three dimensional modelisation describing the propagation of acoustic waves issued from the discharge electric arcs in a passive closed volume. The classical laser working conditions and the non machine-dependent hypotheses relevant to the modelisation allow to extend the conclusions of this study to mostly excimer laser devices. In particular, even though they have been obtained under the single shot regime and without gas flow, the results can be applied to high PRF excimer laser systems. PACS: 42.55.G; 43; 52 Elaboration of reliable high average power excimer devices is of great interest for many industrial applications ranging from microelectronics to medicine and material processing. In that context high pressure electrical discharges commonly considered as the best way to pump excimer laser devices have motivated numerous researches [1–5] to solve the problems related to the discharge homogeneity and instability. Even if technological advances allow to achieve quite non-arc excimer discharges at relatively low Pulse Repetition Frequency (PRF≤∼ 300 Hz), the universal and ultimately unavoidable instability mechanism of excimer discharges [1] still prevents to adjust reliable and efficient high PRF high average power excimer lasers. The increase of excimer laser average power through PRF increase is up to now limited to the kWrange ( ∼1 J×∼ 1 kHz) on a few thousands of shots [6] far from the industrial reliability requirements. This is largely due to aerodynamic phenomena which enhance the onset of discharge instabilities and, consequently, a premature termination of the laser pulse [3], a lowering of its energy [7–9] and a spoiling of its optical quality [10, 11]. The control of the pressure perturbation amplitude is then of fundamental importance to efficiently operate excimer laser systems. As soon as an amount of energy is deposited in a finite gas volume, transient gas dynamic processes lead to the formation of acoustic waves [7, 12, 13]. These acoustic waves reflect on the laser loop and cavity innerwalls and may persist for a long time in the discharge volume. They have to be sufficiently damped before the next energy release to avoid the development of strong non-uniform energy deposition processes. Significant improvements of the active medium homogeneity depend on the comprehension of the aerodynamic phenomena generation and of their evolution in excimer laser devices. In the present work, after a brief description of the X Cl laser used to perform the experiments, we report the most recent approaches about shock wave generation in excimer devices. The discharge spatial and temporal uniformity is characterized by a fast CCD video camera and piezoelectric transducers are used to measure the amplitude of pressure perturbations in the laser cavity. The correlation between discharge quality and pressure field fluctuations is studied through experimental results. At last, a three dimensional modelisation of acoustic wave propagation is presented and this numerical simulation is used to discuss the experiments.