[Abstract] In the present work a numerical study of pressure oscillation frequencies and amplitudes in Ariane 5 MPS P230 boosters will be presented. The study has been conducted by means a commercial CFD package. Validation of the adopted approach has been made on the basis of a cold flow test case. Numerical results have been compared and validated against experimental data, showing in all cases an impressive numerical accuracy. In the case of numerical simulation performed on P230 SRM pressure oscillation amplitude shows a difference lower than 5% when compared with averaged flight data.