The wavelet transform can be used to develop the process which allows group and phase velocity measurement of dispersive waves. The method has been applied to acoustic data to measure formation velocities. The behavior and the accuracy of the method have been checked on synthetic full waveform acoustic data. The method was applied to dispersive waves of the Stoneley type and to flexural modes whose low frequency components are propagated at the formation shear velocity. A raw measurement of the phase velocity of a flexural mode gives an estimate of the shear velocity with an error of about 5%. The use of a wavelet transform yields an accurate study of dispersion and gives a shear velocity measurement with an error of less than 1%. However, all the examples presented here are based on the use of synthetic data, which are not corrupted by noise and were obtained with a numerical model. This algorithm is complete, to the extent in which it enables simulation of all the seismic arrivals for the considered geometry (cylindrical borehole with a circular section, in an homogeneous medium). Nevertheless, such a model remains a simplified version of what will occur in reality, when the irregularities of the borehole, the cementing defects and the background noise may call into question the excellent precision of the results obtained. The process which is described in this paper must be seen as one possible method for the analysis of field data, but it still has to be applied to many recordings of field data before its effectiveness can really be proved.