The short pulse duration and broad bandwidth of attosecond pulses allow the measurement of the phase and amplitude of ionizing electronic wave packets using interferometric techniques. We will present photoionization experiments using the RABBIT (reconstruction of attosecond beating by two-photon transition) method, which enables us to combine high temporal and spectral resolution. This method allows us to gain new insights on the dynamics of the photoionization of atoms (rare gases) and simple molecules, especially in the vicinity of resonances in the continuum.