The present paper discusses the feasibility of frequency analysis of X-ray reflectivity data, which have been used extensively to obtain information on density, layer thickness, surface and interface roughness for layered materials. So far, the experimentally obtained data have been analyzed by least squares fitting to the theoretical reflectivity curve for assumed layered structures. As is often the case with non-linear systems, the solution is not generally unique. In fact, it is sometimes not easy to judge which structural parameters should be selected from several promising candidates that differ from each other to a fair extent but agree quite well with the experimental curve. The problem becomes even worse when one is not confident in the model, i.e., the number of layers etc. Assuming that several additional layers could improve the degree of fit, this raises the question of whether such a model should be accepted or not. The advantages of using frequency analysis, such as Fourier and Wavelet transform techniques, is that one can start from analysis which does not rely on the model too much. As the analysis gives a rough sketch of the electron density profile of the sample, one can decide which models should and should not be chosen. Furthermore, filtering specific frequency components of the data can help to see some morphology changes in the specific interface.